This study aims to investigate whether Butylated Hydroxytoluene (BHT), the synthetic antioxidant and food additive, increases the frequency of micronucleated polychromatic erythrocytes (MNPCEs) in rat bone marrow. BHT, dissolved in corn oil, was administered intraperitoneally to 8-10 week old male and female Wistar rats (n=36) in three different doses (125, 250 and 500 mg/kg b.w.) for two different time periods. 12- and 24-h after BHT treatment, the bone marrow samples were analyzed for the frequency of MNPCEs. Additionally, by evaluating the ratio of polychromatic erythrocyte to normochromatic erythrocyte (PCE/NCE), the cytotoxic effect of BHT on bone marrow was tested. It was found that all BHT doses at two time periods significantly increased the MNPCEs frequency about 1.9-2.84 fold. On the other hand, BHT caused significant decreased in the PCE/NCE ratio, which is indicative of bone marrow cytotoxicity when compared to the control groups. This study showed that BHT increased the formation of MNPCEs in rat bone marrow and we think that this increase might be related to the applied doses and the administration way BHT.