Testicular damage is a comparatively common finding in toxicity studies. Part of the susceptibility of the testis to chemical toxicity stems from the complexity of its normal structure, function and regulatory control. This complexity has stimulated the development and extensive use of testicular cell cultures in the study of normal testicular function. However, the potential of such systems for investigating chemically induced testicular toxicity has only recently been considered. Using primary co-cultures of Sertoli and germ cells many features of the well characterized testicular damage produced by phthalate esters and glycol ethers could be reproduced in vitro. These encouraging findings are discussed in relation to some of the likely limitations to the application of in vitro models for testicular toxicity.