Water extract of the bark of plant of Pterocarpus marsupium Roxb is used as an antidiabetic drug in indigenous medicine in India. (-) Epicatechin, its active principle, has been found to be insulinogenic. The present in vitro study reports some insulin like activities of (-) epicatechin. Like insulin, (-) epicatechin stimulates oxygen uptake in fat cells and tissue slices of various organs, increases glycogen content of rat diaphragm in dose-dependent manner with corresponding increase in U14-C glucose uptake, and inhibits theophylline induced lipolysis in isolated fat pads in dose-dependent manner. Experiments on competitive binding of 125I-insulin and (-) epicatechin to liver cell plasma membrane indicate that insulin does not share binding site with (-) epicatechin. (-) Epicatechin at a concentration of up to 1 mM does not effect the release of glucagon from the islets in vitro. Thus, (-) epicatechin has insulinogenic as well as insulin like properties.