A sexual influence on the hepatic enzymes gulonolactone hydrolase, glueuronolactone hydrolase, gulo-nate NADP oxidoreductase, and gulonolactone O2 oxidoreductase; and on the tissue concentrations of total ascorbate in plasma, liver, lungs, kidneys, spleen, and muscle was shown by comparisons between male and female rats. Males have the higher values for enzymic activities and tissue ascorbate concentrations. The higher enzymic activities at the subcellular level are thought to be the molecular basis for the higher concentrations of ascorbate at the tissue level in males.