Epinephrine (EP), an important neurotransmitter, energizes and speeds up the various body systems and plays an important role during the time of stress and low blood sugar level. There is a close relation between the release of epinephrine and smoking. Edge plane pyrolytic graphite electrode modified with multi-walled carbon nanotubes (MWNTs/EPPGE) has been used as a sensor for the efficient quantitative determination of epinephrine in body fluids of smokers and nonsmokers in resting stage at physiological pH 7.2 by using cyclic voltammetry (CV) and square wave voltammetry (SWV). The oxidation of epinephrine occurred in a well-defined peak having peak potential (E-p) similar to 150 mV at pH 7.2. The limit of detection (3 sigma/slope) and limit of quantification were found to be 0.15 x 10(-9) and 0.48 x 10(-9) M using proposed sensor, respectively. The modified electrode was also utilized for the analysis of commercial sample of epinephrine in order to examine the accuracy of the proposed method. The analytical performance of the modified electrode has been evaluated for quantification of EP in real samples even in the presence of common coexisting biomolecules such as uric acid, ascorbic acid, dopamine and norepinephrine. The voltammetric response of the developed nanosensor towards epinephrine determination in body fluids is fast, sensitive and selective having desirable reproducibility and stability. A comparison of results with high performance liquid chromatography (HPLC) shows a good agreement. (C) 2010 Elsevier Ltd. All rights reserved.