Nonylphenol (NP) is a widely distributed environment contaminant and has been documented to disrupttesticular development and decrease male fertility. Amongst possible targets of this compound aretesticular Sertoli cells, which play a crucial role in supporting and nourishing sperm cells. In the presentstudy,we found that NP treatment could cause dramatic morphological changes aswell as decreased cellviability of Sertoli cells, while the following Annexin V–PI staining demonstrated that NP treatment ledto increased proportion of cell apoptosis, which was evidenced again by the detection of condensationand marginal changes of chromatins using Hoechst staining and transmission microscopy observation.In addition, increased intracellular Ca2+ levels and changes of endoplasmic reticulum (ER) ultrastructurewere also observed in NP-treated groups, indicating the action of NP on ER. The subsequent data showedthat the expressions of ER-stress signaling targeted genes GRP78 and gadd153 were elevated, suggestingthe activation of ER-stress signal pathway. Furthermore, the detection of ER-stress related proteins bywestern blotting revealed that the expression of gadd153was upregulated by NP, whereas the expressionsof GRP78 and ERp57 were both first upregulated and then inhibited. Taken together, it is suggested thatNP can induce ER stress in Sertoli cells, which may plays an important role in the induction of apoptosis.