Toxoplasmosis is one of the most common zoonoses worldwide and up to two third of the worlds population is infected with the parasite Toxoplasma gondii. For immunocompetent humans, this disease normally does not pose any threat. However, it can be dangerous for immunosuppressed individuals and pregnant women who get primarily infected during pregnancy. Because of that, Austria was the first country worldwide to introduce a prenatal screening program for toxoplasmosis in 1975 in order to discover and treat a primary infection during pregnancy as quickly as possible. In this diploma thesis, the seroprevalence of toxoplasmosis antibodies of women in their child bearing years was determined retrospectively using data of mother-child-pass examinations in Vienna and parts of Lower Austria for the years 1998 to 2014 (excluding 2009 and 2012). Toxoplasmosis antibody test results were obtained from a laboratory communication system of a big panel practice, anonymized and evaluated. A decrease of the seroprevalence from 27,5% in the year 1998 to 19,25% in 2014 could be observed. Furthermore, a connection between seroprevalence and age was detected as seroprevalence rates increased with rising age of the mother. Comparing Vienna and other towns in Lower Austria, no significant difference in terms of a urban-rural divide could be observed. However, there was a clear difference of seroprevalence between districts with high income and districts with a low income within the city of Vienna. Here, the seroprevalence was higher in districts which were below average income (19,8%) compared to districts which were above average income (23,6%). Taken together, seroprevalence of T. gondii is decreasing worldwide and reasons for this are multifarious and are examined in this diploma thesis. Also in Austria, seroprevalence of toxoplasmosis has shown a decline over the past few years. All the more, a free-of-cost screening program, which is offered in the framework of the Austrian mother-child-pass, is important so that women from all social classes can be tested for this disease. Discovered in time, effective treatment can be initiated and both mother and child can be brought to further surveillance to prevent more severe complications.