Morbid obesity leads to progressive failure of many human organs and systems; however, the role of oxidative damage to salivary composition is still unknown in the obese patients. In this study, we assessed the effect of bariatric surgery on oxidative damage in nonstimulated (NS) and stimulated (S) whole saliva. The study included 47 subjects with morbid obesity as well as 47 age- and gender-matched healthy volunteers. Oxidative modifications to lipids (4-hydroxynonenal (4-HNE) and 8-isoprostanes (8-isoP)), proteins (advanced oxidation protein products (AOPP) and protein carbonyl groups (PC)), and DNA (8-hydroxy-D-guanosine (8-OHdG)) were analyzed in morbidly obese patients before and after bariatric surgery as well as in the healthy controls. The concentrations of 8-isoP, AOPP, PC, and 8-OHdG were significantly higher in both NS and S of patients with morbid obesity than in the control patients and compared to the results obtained 6 months after bariatric surgery. The levels of oxidative damage markers were also higher in S versus NS of morbidly obese patients. In summary, morbid obesity is associated with oxidative damage to salivary proteins, lipids, and DNA, while bariatric treatment generally lowers the levels of salivary oxidative damage.