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.