We quantified the perception of teratogenic risk in women attending the Motherisk program for counseling about diagnostic radiation in pregnancy (n = 50) and compared it with a control group of women exposed to nonteratogenic drugs and chemicals (n = 48). Before receiving known information about the specific exposure, women exposed to radiation assigned themselves a significantly higher teratogenic risk compared with the control group (25.5 +/- 4.3% versus 15.7 +/- 3.0% for major malformations, P less than 0.01). The post-consultation perception of teratogenic risk did not differ between the two groups. Special consideration and attention should be given when counseling pregnant women exposed to low-dose ionizing radiation, as their misperception of teratogenic risk may lead them to unnecessary termination of their pregnancy.