Pregnant hamsters were treated by topical application of formaldehyde solution on day 8, 9, 10 or 11 of gestation. Fetuses recovered on day 15 were weighed, measured, and examined for teratogenic effects of formaldehyde exposure. The resorption rate was increased in the treated groups, but formaldehyde treatment did not significantly affect weight or length, nor did any malformations which could be related to treatment appear. It was concluded that fetal risk due to maternal topical exposure to formaldehyde is minimal in this model system.