Some chemicals have testicular toxicity to animals and humans. However, their primary toxic targets are different each other, and their detailed mechanisms of toxicity are unclear. In addition, comprehensive protein expression analysis (proteomics) using liquid chromatography-tandem mass spectrometry (LC-MS/MS) is useful for understanding biological reactions in the tissue, and its use has been increasing in recent years. Therefore, in this study, we analyzed the changes in protein expression during repeated administration of testicular toxicants with different toxic targets ethylene glycol monomethyl ether (EGME), 1,3-dinitrobenzene (1,3-DNB), dibromoacetic acid (DBAA), and carbendazim (CBZ), and proposed their respective toxic mechanisms and related biological responses. Test substances were administrated once a day to 8-week-old male SD rats for up to 14 days, and the testes collected from rats were subjected to organ weight measurement, histopathological examination, and proteomics by LC-MS/MS. Pathway analysis were performed for these expression data by Ingenuity Pathway Analysis (IPA) (QIAGEN Bioinformatics). Protein expression analysis revealed different or common test substance-specific changes in pathways or proteins associated with energy production, sperm maturation, Sertoli cell phagocytosis, and testosterone synthesis. Some of these proteins are testis-specific or highly expressed in testis. In this presentation, we would like to discuss the relationship between toxic target differences and variation of pathway patterns.