Sertoli cells are the primary cellular target for a number of pharmaceutical and environmental testicular toxicants, including 2,5-hexanedione, carbendazim, and mono-(2-ethylhexyl) phthalate. Exposure to these individual compounds can result in impaired Sertoli cell function and subsequent germ cell loss. The loss of testicular function is marked by histopathological changes in seminiferous tubule diameter, seminiferous epithelial sloughing, vacuolization, spermatid head retention, germ cell apoptosis, and altered microtubule assembly. The present study investigates dose-response relationships for these classic Sertoli cell toxicants using histopathology endpoints. Understanding the relationship between the Sertoli cell toxicant dose and its histopathologic manifestations will help establish the sensitivity of these endpoints as markers of testicular injury. The results indicate that no single histopathology endpoint was sensitive on its own in identifying altered testicular morphology resulting from toxicant exposure. However, when multiple endpoints were combined dose-response relationships could be associated with incremental alterations in histopathology. The data generated from these experiments will be useful in further investigating the effects of Sertoli cell toxicant exposure in animal toxicity studies. In addition, this work is fundamental to a planned investigation of the histopathologic and gene expression changes associated with testicular toxicant co-exposures, which may occur both occupationally and environmentally.