This stuciv was r,.*"s "T *-#::lilJ"rroootoxic and terarogenic ef- fecis carised bv mebendazole_(ve"ir) on pregnant arbino rats. A singre dose of 0,4.8 and illg/)Kg Uoay *.igtt of frebendr;;; according to Paget and Barnes (r964t *ir uaniinistered-oraliy via poiyethelen gasrric tube ro pregnant rars on 4-6:7-9:10-12 and, tz-is d;y, Jip*gnancy. A dose-depe,dent reduction of the number of foetuses, significant increase in the ferai resoqption rare and a decreur* oi]riuril; ;:ffi, reflected the severe embryolethar and embryoroxic influence .f ;;;;;;ole. A variery of gtoss malformations occurred. skeletal abnormaiities werc observed es_ pecially. liSdrocephalts. hypognathia and rruni"ri"ning-ocete. Also the [1.13]osica].c,hanses or urain ui,a uan.! tissues ,.u"uJ-tt e embryotoxic rntluence of the drug by doses of g and iO *gfl(g.