Othmarschen (German language: pronounced [oːtmaːrʃen]) is a quarter in the Altona borough of the Hamburg in northern Germany. In 2006 the population was 12,169.
The first records on Othmarschen are from 1317. Together with Altona, Othmarschen became a part of Hamburg in 1937/1938 through the Greater Hamburg Act.
In 2006 according to the statistical office of Hamburg and Schleswig-Holstein, the quarter Othmarschen has a total area of 6 km². The western quarter is Nienstedten. In the South the river Elbe is the border to Waltershof. The border in the North to the quarters Groß Flottbek and Bahrenfeld is the railway track of the city train. In the East is the quarter Ottensen.
In 2006, the quarter Othmarschen had a population of 12,169 people. The population density was 2,023 people per km². 16.7% were children under the age of 18, and 22.9% were 65 years of age or older. 11.3% were immigrants. 153 people were registered as unemployed and 2,508 were employees subject to social insurance contributions.