Diabetes is an important human ailment officiating many from various walk of life in different countries. It providing to a major health problem, especially in the rural and subrural areas. Gymnema sylvestre is a herb distributed throughout the world. The leaves of the plant are widely used for the treatment of diabetes and as diuretic in India proprietary medicine. It is used totally all over world for controlling blood sugar. Hence, the study required to be subjected to pharmacological studies in order to discover their effect on the patients who are taking the treatment with synthetic drugs. This study was to determine influence of Gymnema sylvestre on the pharmacokinetics and pharmacodynamics of Oral antihyperglycemic drugs in streptozotocin induced hyperglycemic rats. Results have indicated the negative effect of Gymnema Sylvestre on pharmacokinetics but positive effect on pharmacodynamics of oral hypoglycemic drugs.