The present study was conducted to determine the immunohistochemical changes of whey protein on the male albino rats. Different concentrations were prepared from whey protein were imported from Sports Center for Nutritional Supplements in Baghdad, witch mixed with distilled water and used directly for orally administration. Adult 36 male albino rats were randomly divided into three groups (12 as control and 12 treated with (0.8 g and 12 treated with 1.6 g whey protein, respectively). After 60 days, animals were sacrificed and testis and epididymis were isolated and fixated for immunohistochemical study. The immunohistochemical results in the testis showed increased in the percentage of T lymphocytes which marked by CD3 marker especially in the highest concentration (1.6) g. Also, there was positive staining of B lymphocytes which marked by CD20 marker in the seminiferous tubules and interstitial tissue. In addition, there was weak staining of plasma cells which marked by CD138 marker in the interstitial tissue only. Whereas the vimentin test showed no iimunohistochemical changes were found in the seminiferous tubules and interstitial tissue comparing with control group.