The effects of acute alterations in maternal health status upon fetal development were assessed following exposure of pregnant CD-1 mice on day 8 of gestation to one of ten chemicals at a dose calculated to be the maternal LD10 or LD40. The dams were killed on day 18 of gestation and the fetuses were examined by routine teratological techniques. The chemicals were cacodylic acid, caffeine, deltamethrin, dinoseb, ethylene bisisothiocyanate (EBIS), endrin, guthion, kepone, sodium salicylate, and toxaphene. Three (cacodylic acid, EBIS and kepone) produced dose related increases in the incidence of fully reabsorbed litters. Prenatal mortality in litters that contained live fetuses at term was elevated only for one chemical (cacodylic acid). Fetal weight was reduced in three instances (cacodylic acid, endrin, and guthion), while the incidence of terata was markedly elevated for two (cacoydlic acid and kepone). For two other chemicals (endrine and sodium salicylate), a low incidence was found of defects that were similar to defects induced by those chemicals in other species.