The objective of the study was to examine the human teratogenic potential of oral penicillin V: phenoxymethylpenicillin treatment during pregnancy in the large population-based dataset of the Hungarian Case-Control Surveillance of Congenital Abnormalities, 1980-1996. The dataset included 22,865 pregnant women who had fetuses or newborns with congenital abnormalities and 38,151 matched pregnant women who had newborn infants without any congenital abnormality (population control group). Of 22,865 case pregnant women, 173 (0.8%) had phenoxymethylpenicillin treatments, while of 38,151 population controls, 218 (0.6) were treated by this penicillin V (crude OR 1.3 with 95% CI: 1.1-1.6). This difference was explained mainly by recall bias and confounders because adjusted OR for medically documented phenoxymethylpenicillin treatments did not show difference during the second-third months of gestation, i.e. in the critical period for most major congenital abnormalities in case-matched control pairs. Thus, treatment with oral phenoxymethylpenicillin during pregnancy presents very little if any teratogenic risk to the fetus.