Toxoplasmosis in pregnant women can lead to congenital disease with severe neurological and ocular complications in the foetus. In 2006, we surveyed US obstetrician–gynaecologists to determine their knowledge and practices about toxoplasmosis prevention and testing. Questionnaires were mailed (four mailings) to a random sample of 1200 of the 33 354 members of the American College of Obstetricians and Gynecologists (ACOG). Of the 1200 surveyed, 502 (42%) responded. The respondents were similar to all ACOG members by gender, region of the country and practice type (P > 0.5), and age (respondents were slightly younger, mean 46 years versus 47 years). To prevent toxoplasmosis, most respondents indicated that they counsel pregnant women about cat litter (99.6%), but fewer counselled about eating undercooked meat (77.6%), handling raw meat (67.4%), gardening (65.4%) or washing fruits and vegetables (34.2%). Many (73.2%) respondents were not aware that some Toxoplasma IgM tests have had a high false positive rate, and most (91.2%) had not heard of the avidity test, which can help determine the timing of Toxoplasma gondii infection in relation to pregnancy. There is a need for more education about T. gondii serological testing, particularly the Toxoplasma avidity test. US obstetrician–gynaecologists are providing beneficial counselling to their patients, but could provide more information about undercooked meat and soil risks.