Capillary isotachophoresis was applied for the determination of fendiline and gallopamil--calcium antagonists--in serum. The cationic electrolyte system containing Na+ with acetic acid as a counter constituent was used as a leading electrolyte with the pH 4.7 and the terminating electrolyte was beta-alanine. Most of the proteins were precipitated with methanol, ethanol and dimethylketone. The lowest limits of quantitation were obtained for the pretreatment of serum with methanol. The recoveries of both compounds varied from 91.3 to 97.5%. The relative standard deviations varied from 0.6 to 7.7%.