The therapeutic efficacy of pooled bovine colostrum for the control of cryptosporidiosis was investigated during murine acquired immunodeficiency syndrome in female C57B1/6 mice. Mice were infected with LP-BM5 murine leukemia retrovirus for four months and then inoculated with Cryptosporidium parvum oocysts. Persistent cryptosporidiosis was established in all retrovirus immunosuppressed mice, while control mice were refractory to infection. Parasite colonization of intestinal villi was significantly (P < 0.05) reduced in immunosuppressed animals that received dietary supplemental pooled bovine colostrum compared with to those that did not receive colostrum treatment. Similarly, shedding of oocysts in the feces of immunosuppressed animals that received dietary pooled bovine colostrum was significantly (P < 0.05) reduced compared with those that did not at 26 days post-parasite challenge. Since the nonimmune bovine colostrum contained no anti-Cryptosporidium antibodies, this suggests that passively transferred antibodies alone are unlikely to have provided the improved resistance shown in this study.