A series of sulfamate salt derivatives of the potent and selective 2-(4-aminophenyl)benzothiazole antitumour agents has been prepared and their evaluation as potential prodrugs for parenteral administration carried out. The salts were sparingly soluble under aqueous conditions (pH 4-9), and degradation to the active free amine was shown to occur under strongly acidic conditions. The salts were found to be markedly less active than their parent amines against sensitive human tumour cell lines in vitro.