Abstract: To investigate apoptosis and localization of apoptotic related proteins in alpaca testis during the process of postnatal development and spermatogenesis, testicular tissues were collected from male alpacas at neonatal, 12 and 24 months of age. Apoptotic activity was studied by TUNEL (terminal deoxynucleotidyl transferasemediated dUTP nick end labeling) method, the distribution of apoptotic related proteins Caspase3 and Bcl2 in testes were examined by immunohistochemical method. Results showed that TUNELpositive cell wasn′t observed in neonatal testis. While Caspase3positive and Bcl2positve cells were observed in the interstitial compartment of neonatal testes. These indicated that apoptotic proteins involved in the apoptotic process of interstitial cells, and gave a space for seminiferous development. In the testes of 12monthold alpacas, TUNELpositive cells were observed in the central part of seminiferous, Caspase3positive and Bcl2positive cells were observed in the interstitial compartment and central part of seminiferous. These founding gave a clue that apoptosis and apoptotic proteins involved in the process of lumen′s formation of seminiferous of puberty (12monthold) alpaca testis. At 24 months of age, TUNELpositive cells were observed in the spermatogonia, spermatocytes and spermatozoa, Caspase3positive and Bcl2positive cells were observed in the interstitial compartment and all stages of germ cells. Caspase3 localized mainly in the spermatogonia and early spermatocytes, while Bcl2 took a preferential adluminal compartment staining pattern in the seminiferous tubules. These results indicated that apoptosis mainly occurred in spermatogonia and early stage of germ cells development, Bcl2 might inhibit the germ cell death of postspermatocyte during the process of spermatogenesis. Apoptosis involved in the process of postnatal testes development and spermatogenesis in alpaca. Apoptotic related proteins Caspase3 and Bcl2 involved in the regulation of apoptosis during the process of postnatal development and spermatogenesis in alpaca.