Zidovudine (AZT), the first drug approved for the treatment of AIDS, has been reported to induce drug efflux transporter systems in different tissues. Overexpression of P-gp and multidrug resistance proteins (MRPs) has been reported in the immune and central nervous system cells when exposed to AZT. In this work we studied the transport of AZT through rat small intestine segments using the everted gut sac technique, evaluating the amount of drug transported, flux and apparent permeability coefficient at different concentrations and times of exposure. We observed a constant transport ratio from the mucosal to the serosal side of the segments corresponding to yeyunum at all concentrations, while for ileum the ratio was constant at low concentrations. A decrease in the amount of drug transported with the increase of time exposure was observed at higher concentrations in ileum. Serosal to mucosal transport assay evidenced an increase in the ratio of drug transported with respect to time at high drug concentration. These results allow us to conclude that the expression of efflux transporters may occur for AZT in rat small intestine, although further assays using inhibitors are needed to identify the system involved.