The present work aimed to evaluate the antitumor activity of tetrodotoxin (TTX) extracted from the Red Sea puffer fish, Lagocephalus sceleratus on the liver and kidney functions of Ehrlich Solid Carcinoma (EAC) bearing male albino mice. The puffer fishes were collected from the commercial catches at the Attaka fish landing station, Suez Governorate, Egypt. After 10 days of induction by Ehrlich Solid Carcinoma (EAC) cells, Ehrlich Solid Carcinoma (ESC) tumor inthigh musclesof induced mice was appeared and this time represented the zero day of the experiment. A sublethal dose of extracted TTX was administrated to mice having Ehrlich Solid Carcinoma (ESC) tumor, for a period of 3 weeks in nine equal doses (each 48 hours). Injection of TTX to mice specimens having Ehrlich Solid Carcinoma (ESC) tumorin G₄resulted in a highly significant decrease in hepaticASAT and ALAT enzyme activities(P<0.01)after the third week of the experiment, compared with that of G₃.Also, the injection of TTX highly significant (P<0.05) improved the kidney functions (urea and creatinine) in mice specimens having Ehrlich Solid Carcinoma (ESC) tumorspecimens(G₄), comparing with that of G₃ mice specimens.