During 1995--1996 a population-based seroprevalence study was conducted in The Netherlands. Risk factors were established for postnatally acquired toxoplasmosis. The results were compared with a study conducted during 1987-1988 in pregnant women in the Southwest of The Netherlands in order to estimate the change in seroprevalence. In total, 7521 sera were tested and the national seroprevalence was 40.5 % (95 % CI 37.5-43.4). Living in the Northwest, having professional contact with animals, living in a moderately urbanized area, being divorced or widowed, being born outside The Netherlands, frequent gardening and owning a cat were independently associated with Toxoplasma seropositivity. Risk factors like eating undercooked meat could not be studied. The seroprevalence among women aged 15-49 years was 10 % lower (35.2 %, 95 % CI 32.9-38.6) in the study of 1995-1996, compared to the Toxoplasma study of 1987--1988 (45.8 %, 95 % CI 45.2-46.3). The steepest rise in seroprevalence still occurred among the subjects aged 25-44 years.