The absorption of 4 different sulfonamides (sulfamethoxypridazine, sulfadimethoxine, sulfisoxazole, and sulfasy-mazine) was apparently delayed but not reduced by concomitant administration of food following single oral doses of each compound in the recommended dosage schedule. Sulfasymazine was excreted more rapidly than either sulfamethoxpyridazine or sulfadimethoxine, although not as rapidly as sulfisoxazole; this suggests that sulfasymazine occupies a position intermediate between the long-acting and short-acting sulfonamides.