Literature was surveyed concerning the teratological testing of chemicals, to which large numbers of workers are occupationally exposed. They include metals, plastics monomers and additives, solvents, and other organic chemicals. The effective doses used in the studies were compared to the potential exposures in the occupational environment as regulated by hygienic standards. In light of the animal experiments, the TLVs for some organic chemicals, particularly for acrylonitrile, methacrylate esters, styrene, carbon disulfide, chloroform, methylene chloride, toluene and xylene, appeared too high to provide absolute safety for pregnant workers. The mechanisms of teratogenesis and the validity of the animal experiments were also considered.