Densitometry was used for quantitative determination of arbutin (Vaccinium vitis idaeae) in leaves of cowberry collected from region of Suwalszczyzna, Poland. Arbutin was extracted using methanol. Chromatography was performed on glass TLC plates with layers of silica gel. The quantitative densitometric analysis was performed using internal standard solution method. On the base of densitometric analysis it was shown that the band characteristic for absorption maximum of arbutin is placed at lambda(max) = 285 nm. The second absorption band is at lambda = 225 nm. It was stated that contents of arbutin are ca. 35 mg and 47 mg in 1 g of herbs, in cowberry leaves coming from collections in 2005 and 2006 year, respectively. The presented method is accurate, selective, and precise, and can be used for routine quality control analysis and quantitative determination of arbutin in cowberry leaves.