Abstract Recent studies showed that nonhuman primate TRIM5α can efficiently block HIV-1 infection in human cell lines. It can also restrict other retroviruses, therefore, suggested as a general defender against retrovirus infection. Here, we present an evolutionary analysis of TRIM5α in primates. Our results demonstrated that TRIM5α has been evolving rapidly in primates, which is likely caused by Darwinian positive selection. The SPRY domain of TRIM5α, which may be responsible for recognition of incoming viral capsids showed higher nonsynonymous/synonymous substitution ratios than the non-SPRY domain, indicating that the adaptive evolution of TRIM5α in primates might be an innate strategy developed in defending retrovirus infection during primate evolution. In addition, the comparative protein sequence analysis suggested that the amino acid substitution pattern at a single site (344R/Q/P) located in the SPRY domain may explain the differences in susceptibilities of HIV-1 infection in diverse primate species.