Toluene and 5 aliphatic chlorinated hydrocarbons of wide industrial use were injected into the air space of fertilized chicken eggs at 2,3 and 6 days of incubation. The embryotoxicity was evaluated as survival and death incidences after 14 days of incubation, and also the the weights and lengths of the embryo were recored. The approximate LD50 value for trichloroethylene and trichlorethanes varied between 50 and 100 μmol/egg while for toluene, tetrachlorethylene and methylene chloride it was over 100 μmol/egg. Macroscopic malformations of various kinds were produced with doses of 5-100 μmol/egg. The teratogenic potential of the tested compounds decreased in the following order: 1,1,1-trichloroethane > trichloroethylene > methylene chloride, tetrachloroethylene, 1,1,2-trichloroethane > toluene > olive oil control. © 1979.