It was Simoni's second win in the Giro. After the race, it was discovered that sixth-placed Raimondas Rumšas had tested positive in this Giro.
This edition of the Giro was the first UCI endorsed race where the wearing of helmets was compulsory.
With Gilberto Simoni's general classification victories in 2003 and in 2001, Simoni became the eighteenth rider to repeat as winner of the Giro d'Italia. In addition to the general classification, Simoni also won the points classification. In the race's other classifications, Colombia–Selle Italia rider Fredy González won the mountains classification and Magnus Bäckstedt of the Team Fakta-Pata Chips team won the intergiro classification.[1]Lampre finished as the winners of the Trofeo Fast Team classification, ranking each of the nineteen teams contesting the race by lowest cumulative time.[1] The other team classification, the Trofeo Super Team classification, where the teams' riders are awarded points for placing within the top twenty in each stage and the points are then totaled for each team was won by Fassa Bortolo.[1]
A total of 19 teams were invited to participate in the 2003 Giro d'Italia.[2] Each team sent a squad of nine riders (only Kelme–Costa Blanca started eight), so the Giro began with a peloton of 170 cyclists.[2] Out of the 170 riders that started this edition of the Giro d'Italia, a total of 97 riders made it to the finish in Milan.[1]
Monte Zoncolan was climbed from eastern side of the mountain where the climb begins in Sutrio. The mountain hosted the end of the 185 km (115 mi) twelfth stage.
The route for the 2003 Giro d'Italia was unveiled by race director Carmine Castellano on 30 November 2002 in Milan.[3] It contained two time trial events, all of which were individual. The organizers divided the remaining eighteen stages into three categories: flat stages, rolling stages, and mountain stages. Twelve of the stages were declared flat stages. Of the seven stages remaining, three stages were designated rolling stages and three were ranked as mountain stages. In the stages containing categorized climbs, six had summit finishes: stage 3, to Terme Luigiane;[4] stage 7, to Monte Terminillo;[5] stage 12, to Monte Zoncolan;[6] stage 14, to Alpe di Pampeago;[7] stage 18, to Chianale;[8] and stage 19, to Cascata del Toce.[9] The organizers chose to include two rest days. When compared to the previous year's race, the race was 122 km (76 mi) longer, contained the same amount of rest days, and one less individual time trial. In addition, this race lacked an opening prologue like the previous year had.
In the 2003 Giro d'Italia, five different jerseys were awarded. For the general classification, calculated by adding each cyclist's finishing times on each stage, and allowing time bonuses for the first three finishers on mass-start stages, the leader received a pink jersey. This classification is considered the most important of the Giro d'Italia, and the winner is considered the winner of the Giro.[11]
The Colle d'Esischie was the Cima Coppi for the 2004 Giro d'Italia.
Additionally, there was a points classification, which awarded a mauve jersey. In the points classification, cyclists got points for finishing in the top 15 in a stage. The stage win awarded 25 points, second place awarded 20 points, third 16, fourth 14, fifth 12, sixth 10, and one point fewer per place down the line, to a single point for 15th. In addition, points could be won in intermediate sprints.[11]
There was also a mountains classification, which awarded a green jersey. In the mountains classifications, points were won by reaching the top of a mountain before other cyclists. Each climb was categorized as either first, second, or third category, with more points available for the higher-categorized climbs. The highest point in the Giro (called the Cima Coppi), which in 2003 was the Colle d'Esischie, afforded more points than the other first-category climbs.[11]
The fourth jersey represented the intergiro classification, marked by a blue jersey.[11] The calculation for the intergiro is similar to that of the general classification, in each stage there is a midway point that the riders pass through a point and where their time is stopped. As the race goes on, their times compiled and the person with the lowest time is the leader of the intergiro classification and wears the blue jersey.[11]
There were also two classifications for teams. The first was the Trofeo Fast Team. In this classification, the times of the best three cyclists per team on each stage were added; the leading team was the team with the lowest total time.[11] The Trofeo Super Team was a team points classification, with the top 20 placed riders on each stage earning points (20 for first place, 19 for second place and so on, down to a single point for 20th) for their team.[11]
The rows in the following table correspond to the jerseys awarded after that stage was run.
Other less well-known classifications, whose leaders did not receive a special jersey, were awarded during the Giro. Other awards included the Combativity classification, which was a compilation of points gained for position on crossing intermediate sprints, mountain passes and stage finishes.[11] Colombian Fredy González won the Most Combative classification.[1] The Azzurri d'Italia classification was based on finishing order, but points were awarded only to the top three finishers in each stage.[11] The Azzurri d'Italia classification was won by Gilberto Simoni.[1] The Trofeo Fuga Piaggio classification rewarded riders who took part in a breakaway at the head of the field, each rider in an escape of ten or fewer riders getting one point for each kilometre that the group stayed clear.[11] The classification was won by Constantino Zaballa.[1] Teams were given penalty points for minor technical infringements.[11]Colombia–Selle Italia was the most successful in avoiding penalties after not being penalized during the race, and so won the Fair Play classification.[1]
^"Cinco metas para escaladores" [Five goals for climbers] (PDF). El Mundo Deportivo (in Spanish). 1 December 2002. p. 44. Archived(PDF) from the original on 4 March 2016. Retrieved 27 May 2012.
^"86° Giro d'Italia – Il Regolamento" [86th Giro d'Italia – The Regulations] (PDF). La Gazzetta dello Sport (in Italian). 2003-04-29. pp. 1–24. Archived from the original on 2016-03-04. Retrieved 2012-09-30.
Alessandro Petacchi (ITA)
Robbie McEwen (AUS)
Kurt Asle Arvesen (NOR)
Aitor González (ESP)
Serhiy Honchar (UKR)
Georg Totschnig (AUT)
Ján Svorada (CZE)
Magnus Bäckstedt (SWE)
Fredy González (COL) 
Sandy Casar (FRA)
