The simultaneous determination of atropine and scopolamine derivatives, which have similar structures, was investigated by using capillary zone electrophoresis. The effects of buffer pH, buffer concentration and hydroxypropyl-beta-cyclodextrin concentration on migration time and resolution of the investigated compounds were systematically studied. The selected electrophoretic buffer consisted of a 80 mM sodium citrate pH 2.5, containing 2.5 mM hydroxypropyl-beta-cyclodextrin as the complexing agent. Quantitative analysis was validated by testing the reproducibility of the method, giving a relative standard deviation less than 1 and 2% for the intermediate precision of migration times and peak area ratios, respectively. The linearity of the method was assessed between 50 and 150% of the theoretical content (coefficient of correlation greater than 0.99). The proposed method was found to be suitable and accurate for the determination of these basic drugs in pharmaceutical preparations.