Metabolism of L-ascorbic acid 2-sulfate (2-O-sulfonate L-ascorbic acid: AsS) has been studied by use of rainbow trouts (body weight 200 g) and guinea pigs (Hartley strain, body weight 200 g) on intubation of various amount of AsS. The AsS levels of blood and liver in AsS intubated animals were determined by Bromine-Hydrazine method (Vitamins, 52, 541 (1978)). In guinea pigs on intubation of 0.1 mmol AsS/body weight 100 g, AsS contents in tissues attained to maximum concentration at 30 min in blood (12.0 μg/ml) and liver (12.2 μg/g). In rainbow trouts on oral intake of 0.1 mmol AsS/body weight 100 g, at 3 h in blood (13.3 μg/ml) and 6 h in liver (51.6 μg/g), respectively. The rapid clearance of AsS in blood and liver were one of the possible reasons for the absence of an antiscorbutic effect with AsS in the guinea pig. In the rainbow trout, AsS was metabolized more slowly than in case of guinea pigs and ascorbic acid liberated from a part of incorporated AsS increased in trout tissues.