Capillary electrophoresis (CE) was applied to photostability studies on rac-nicardipine, a dihydropyridine chiral drug. CE methods were developed able to provide the enantioresolution of drug and its separation from the photodegradation products. Enantio-resolution was achieved using 5% sulfated-beta -cyclodextrin (S-beta -CD) as chiral selector in 20 mM triethanolammonium phosphate solution (pH 3). The photostability studies were carried out on inclusion complexes of rac-nicardipine with beta -cycloclextrin (beta -CD) and (2-hydroxypropyl)-beta -cyclodextrin (HP-beta -CD) in aqueous solutions (pH 7.4 and 5). The CE analysis of the solutions exposed to UV-A and UV-B radiations showed a photoprotective effect by beta -CD; conversely, HP-beta -CD proved to favor the drug photodegradation. Moreover, evidences for CDs-mediated stereoselective photodegradation of rac-nicardipine were obtained. In fact, two distinct photodegradation profiles were observed for the nicardipine enantiomers in the presence of the CDs. The photodegradation was found to follow an apparent first-order kinetics and two different kinetic constants (k) were obtained for the two enantiomers. After exposure to UV-A and UV-B radiations, the solutions contained residual nicardipine with a significant change in the enantiomeric ratio; this effect was depending on the CD used for the inclusion complexation.