Organotypic cultures of dorsal root ganglia (DRGs) were isolated from 12-day-old chick embryos and cultured in a semi-solid medium for use as a model for toxicological studies. The mean radial length of neuritic processes growing out from the ganglia, the daily rate of neurite elongation, and the area of neurite outgrowth were used as parameters to evaluate the toxic influence of three drugs (cisplatin, taxol and chlorpromazine) that have neurotoxic side-effects through different modes of action on the peripheral nervous system. A significant, dose-dependent decrease of all parameters of neurite outgrowth was observed in cultures treated with different concentrations of the chemicals tested. We conclude that the culture system described here may be a useful in vitro method to test target organ toxicity in the peripheral nervous system.