Total phosphorus, inorganic phosphorus and phosphocreatine were determined in trichloracetic acid extracts of fish skeletal muscle, and the acid extracts were then fractionated for the determination of adenosine polyphosphates, fructose mono and diphosphates, glucose monophosphates, myoadenylic acid, pentose phosphate and coenzyme, while glycogen was determined in the extracted tissue. A comparison of the distribution of these compounds in fish and rat skeletal muscle was made.