Neurotoxicity of acrylamide and related compounds and their effects on the testis after repeated oral doses were studied in mice. Of fourteen analogues tested, five produced neuropathy. In decreasing order of potency as assessed by the rotarod performance test, these were as follows: acrylamide > N-isopropylacrylamide > N-methylacrylamide = methacrylamide > N-hydroxymethylacrylamide. The development of neurotoxicity was either greatly reduced or delayed by phenobarbital treatment. Acrylamide, N-hydroxymethylacrylamide, N-isopropylacrylamide, N-methylacrylamide and N,N′-methylene-bis-acrylamide produced testicular atrophy. Atrophy was either prevented by phenobarbital treatment, as in the cases of acrylamide and N-isopropylacrylamide, or reduced, as in the case of N-hydroxymethylacrylamide. Histological changes in the testis produced by the active compounds were degenerations of the epithelial cells of the seminiferous tubules, with the interstitial cells being normal.