Capillary isotachophoresis was employed to separate and determine dimethinden enantiomers in various dosage forms. Several types of chiral selectors were tested in various electrolyte systems of different composition and different pH. The optimal leading electrolyte was composed of 10 mmol/l potassium acetate and acetic acid to achieve pH 4.8 with an addition of 4 mmol/l carboxyethyl-beta-cyclodextrin as the chiral selector and 0.2% of methylhydroxyethylcellulose (m-HEC) to suppress the electroosmotic flow. The terminating electrolyte was betaalanine of a concentration of 5 mmol/l. The evaluation included the precision, correctness, linearity, robustness, and selectivity of the elaborated ITP method. The pretreatment of the sample prior to analysis consisted in the dissolution and dilution of the appropriate dimethinden-containing dosage form with demineralized water to achieve the required concentration. Such a pretreated sample was directly dosed into the apparatus.