In mature male and female SD rats, the anti-weight gain effect of durabolin plus vitamin C or vitamin C alone was statistically significant compared to durabolin-treated and control rats. The anti-tumor and anti-weight gain effects of MAP plus vitamin C on DMBA-induced rat mammary cancer were compared with those of MAP and vitamin C in relation to ER. An anti-tumor effect was noted in the MAP treated groups, irrespective of the ER status; it was more pronounced in the MAP (100 mg/kg) plus vitamin C treated group with ER+tumors. Among the ER+tumor groups, weight gain was remarkable in the MAP-treated (20 mg/kg) animals; an anti-weight gain effect was seen in the MAP (20 mg/kg) plus vitamin C group.