Objective: The aim of this study was to test the action of Porphyrin compounds, Tetraphenylporphine sulfonate (TPPS), 5,10,15,20-Tetrakis (4-sulfonatophenyl) porphyrinato Iron(III) Chloride (FeTPPS) and 5,10,15,20-Tetrakis (4-sulfonatophenyl) porphyrinato Iron(III) nitrosyl Chloride (FeNOTPPS), on Na+, K+ -ATPase of cell membrane of erythrocytes., Methods: Enzymatic assays, measuring the amount of inorganic phosphate produced, were used to estimate the activity of Na + , K + -ATPase., Results: The results show that Porphyrin compounds exert an insulin-like effect on Na + , K + -ATPase. They act by increasing the activity of the membrane-bound enzyme., Conclusion: All the three Porphyrin compounds increased the activity of erythrocyte Na + , K + -ATPase. The exact mechanism of action of these compounds is not clear.