[en] Most of the salicin present in willow stem bark occurs as labile glycosides (e.g. salicin, salicortin, 2-O'-acetylsalicortin, 3-O'-acetylsalicortin, tremulacin and fragilin). On alkaline hydrolysis, these acylated derivatives decompose to salicin; in this way, the total amount of salicin can be determined. A HPTLC method has been developed for the quantitative determination of salicin in stem bark before and after alkaline hydrolysis. The mobile phase used for the separation is a modification of one described in the literature. a double or triple migration is necessary to separate salicin from other components of the extract. The results have been compared with those obtained after bidimensional chromatography using two phases described for the quantitative evaluation of salicin. to check that separation was complete, the spectrum of salicin obtained from willow extracts was superimposed on that of a salicin standard.Quantification was performed at lambda = 270nm, the wavelenght of maximum absorption in the IV spectrum of salicin.