Hyperlipidaemic diets induce increase in serum lipid profile (total cholesterol, triglycerides, LDL etc). It has also been proven that stress interferes in lipid metabolism. Many drugs modify their pharmacokinetic properties in presence of lipoproteins, as a result of alterations in their plasma protein and tissue binding. Lidocaine, a synthetic amide, used as a local anesthetic and secondary as antiarrhythmic agent is also protein bound and therefore conditions, which favor lidocaine dissociation from plasma proteins, modify its pharmacokinetic profile. The purpose of this study was: To investigate and compare the effects of stress( cold water 4 degrees C swimming of 20 days duration) and various high lipid diets (olive oil, butter, sunflower oil) on the serum and tissue (liver and tongue) levels of 14C lidocaine.