Ochratoxin A (OTA) is a mycotoxin produced by species of the genus Aspergillus and penicillium. Human exposure has been demonstrated worldwide and its origin seems to be the intake of contaminated foods. Immunotoxic and genotoxic effects of OTA were investigated in mature male albino rats, when treated with garage in a close of 150, 300 and 450 OTA μg/kg B.wt. for 90 days. In the context several immune function assays were performed and bone marrow smears were obtained and stained in order to analyse micronuclei in polychromatic erythrocytes. The response of splenocytes to sheep red blood cells was decreased in a dose –dependent manner. However, slightly statistically significant differences were obtained. Cytotoxic T lymphocytes activity was lower in the animals exposed to 150 OTA μg/kg B.wt. but was not modified in the groups exposed to 300 & 450 μg/kg B.wt.. The number of micronuclei in bone marrow polychromatic erythrocytes was slightly increased with respect to the control at any dose.