The present study focuses on the in vitro interaction between snake venom and electrolytes and Na+, K+-stimulated ATPase system in number of tissues from humans and animals. The venom produced a change in the resting cellular sodium and potassium levels in all the tissues tested. When compared, only human cancerous tissue showed apparent fall in sodium and a rise in potassium, while no significant change occurred in normal. The effect of snake venom (25 microg/ml) on sodium pump activity, a transport enzyme, was assessed in normal tissues. Human erythrocyte membrane pump was significantly inhibited than-rabbit heart and liver tissue. With subsequent increase of dose no further change took place in these cells. A non significant and comparable stimulation in the enzyme activity was seen with rabbit heart and liver. These findings demonstrate that human erythrocytes are more sensitive towards the venom and secondly that venom might potentiate its cellular function by modifying the sodium pump activity.