3-Hydroxypropyl- and 2, 3-dihydroxypropyl-β-cyclodextrins (3-HP- and DHP-β-CyDs) with different degrees of substitution (D.S.) were prepared and their pharmaceutical properties were investigated. The aqueous solubility of 3-HP- and DHP-β-CyDs was much higher than that of the parent β-CyD and the dissolution of DHP-β-CyD in water was endothermic. The acid- and α-amylase-catalyzed hydrolysis rates of 3-HP- and DHP-β-CyDs were slower than those of the parent β-CyD. The hemolytic activity (human erythrocytes) and local irritancy (rabbit muscle) of DHP-β-CyD were considerably less than those of natural, methylated or other hydroxyalkylated β-CyDs, and decreased with increasing D.S. The ability of the hydroxyalkylated β-CyDs to remove cholesterol and proteins from human erythrocytes decreased with increasing D.S., and correlated well with their hemolytic activity. 3-HP-β-CyD was a more effective solubilizer for poorly water-soluble drugs than the parent β-CyD, and its stabilizing effect on chemically instable drugs was higher than that of the parent β-CyD. The above data suggest a considerable pharmaceutical potential of 3-HP- and DHP-β-CyDs as parenteral carriers.