Cytosolic sulfation of arylamines to form sulfamates is found to be mediated by sulfotransferases of three gene families (SULT1 to 3). Among them, a SULT3 form (ST3A1) showed a high selectivity for N-sulfation of N-substituted aryl and alicyclic compounds. SULT1 (phenol) and SULT2 (hydroxysteroid) sulfotransferases showed N-sulfating activities of carcinogenic heterocyclic amines. For N-hydroxyarylamine O-sulfation, SULT1 forms showed high activity. In rats, ST1C1 mediated the metabolic activation of N-hydroxyarylamines. However, the related form (ST1C2) in humans showed the negligible activity. Instead, ST1A3 showed high metabolic activating abilities among human sulfotransferases.