Sex differences in taste aversion learning have been reported for a number of different compounds. It is unknown, however, to what degree, if any, such differences exist when nicotine is the aversion-inducing agent. To address this issue, in the present experiment male and female rats were given limited access to saccharin followed by an intraperitoneal (i.p.) injection of either vehicle or nicotine (0.4, 0.8 or 1.2 mg/kg). Although nicotine induced significant taste aversions in both males and females, the aversions were generally weak at all doses tested. There were no sex differences in the acquisition or strength of the aversions induced by nicotine. The vulnerability to drug abuse has been suggested to be a function of the balance of the rewarding and aversive effects of a drug. Given the relatively weak aversions induced in both sexes and the absence of differences between males and females, it is unlikely that the reported sex difference in the self-administration of nicotine is a function of differences in nicotine's aversive effects. The reported difference in the self-administration of nicotine by males and females is more likely a function of differences in the sensitivity to the rewarding effects of the drug.