Experiments on mice and rats with alloxan diabetes were conducted for comparative assessment of the effectiveness of therapeutic use of adaptogenic plant pharmaceuticals as well as some other commonly used plant drugs. Of marked antidiabetic properties were root and leaf ginseng tincture (LGT), Echinopanax tincture, extracts of Eleutherococcus, Rhodiola (ER) and Leuzia which decreased the blood level of glucose in a CTT (5 g h of glucose per I kg of the animal body mass) from 17.15 to 11.19, 11.50, 12.72, 11.69, 13.47 mmol/l and increased the alloxan-reduced level of liver glycogen by 50-80% (P less than 0.05). Aralia and Schizandra tinctures for this diabetic model were ineffective. Yarrow, everlastings and birch leaf tea also possessed marked hypoglycemic and glycogen sparing properties. The most effective experimentally plant adaptogens LGT and ER increased the blood level of insulin in alloxan diabetic rats in a GTT from 16.75 up to 44.42, 35.31 microU/ml and decreased the level of glucagon from 495 to 195 and 138 pg/ml, respectively. The authors discussed mechanisms of antidiabetic, insulinotropic and hypoglucagonemic action of the effective plant pharmaceuticals and the prospects of their use in multimodality therapy of diabetes mellitus of type I.