A variety of derivatives of 2-pyridinecarboxaldehyde 1-oxide benzenesulfonylhydraone, containing substituents on the benzene or pyridine rings as well as on the nitrogen atom which is bonded directly to the sulfonyl group, have been synthesized. The antineoplastic activity of these compounds has been assessed in mice bearing either leukemia L1210 or P388. The most potent agents in this series were 2, 4-dimethoxy-, 3, 4-dimethoxy-, and 2, ...