For glibenclamide bioavailability studies in serum, high-performance liquid column and thin-layer chromatographic methods were introduced. Both methods are specific, accurate and sensitive with detection limits of at least 5 ng of glibenclamide per ml of serum. Detection is performed in the ultraviolet at wavelengths of 200 nm for liquid chromatography or 300 nm for thin-layer chromatography. Serum levels determined by either method correlated well with those determined by an already existing radioimmunoassay. Some pharmacokinetic data were computed using a one-compartment open model.