The transport of alendronate through Caco-2 monolayers in the absence and presence of absorption enhancers (sodium taurocholate-STC and dimethyl-beta-cyclodextrin-DM-beta-CD) was studied. The viability of Caco-2 cells was determined by MTT assay. The effects of the experiment period and serum existence in Dubelco's Modified Eagle's Medium (DMEM) on cell viability were examined. The least toxic concentrations of alendronate, STC and DM-beta-CD were found as 0.2% (w/v), 5 mM and 0.3% (w/v), respectively. Transport experiments were performed with these concentrations in DMEM supplemented with serum for an 8 h period. DM-beta-CD increased the transport of alendronate through Caco-2 monolayers significantly. No significance was observed with STC. Cell integrity was determined by measuring the electrical resistance values at the end of the transport experiments and found to be decreased to a greater extent with DM-beta-CD. These results indicate that DM-beta-CD is a promising agent for improving the transport of alendronate.