The results of a study of the effects of hydroxyl groups at positions, 2, 4 and 6 of the amino sugar on the activity of daunorubicin, adriamycin, and stereoisomers are presented. While the 4'-deoxy derivatives showed a slightly increased biological activity as compared with the parent compounds, the derivatives containing an additional hydroxyl group were less active. It is suggested that the changes in the polarity and in the DNA binding ability of these derivatives are the main factors accounting for the difference in the in vivo activity. The possible relations among the pKa values, the DNA binding properties, and the cellular uptake of the compounds are discussed with particular reference to their therapeutic effectiveness.