AbstractNoradrenaline levels in skeletal muscle extracts purified by cation exchange chromatography were analyzed fluorimetrically by the THI procedure. The average amount of nor‐adrenaline found in muscles from different species varied between 0.031 and 0.119μg/g. Adrenaline was found only in minute amounts, never constituting more than 11% of the sum of noradrenaline and adrenaline. In the cat, a constant relation was found between the noradrenaline values in different muscles. Preganglionic sympathetic denervation caused a slight increase in muscle noradrenaline during the first days. Noradrenaline levels in the muscles tended to rise during the first two days after postganglionic sympathetic denervation, only to decline abruptly after about 48 hours. Forteen days after postganglionic denervation the muscles were practically devoid of noradrenaline, indicating that skeletal muscle noradrenaline is stored almost exclusively in postganglionic sympathetic nerv