As part of our continuing routine toxicologic evaluations of the products of Amoco Oil Company, a wholly-owned subsidiary of Standard Oil Company (Indiana), we initiated lifetime, mouse skin-painting studies with samples of furnace oil and diesel fuel. The studies consisted of 50 male C3H mice exposed twice weekly to 50 microliters of undiluted test material, for the lifetime of the animals. The material was applied to the clipped unabraded dorsal surfaces with no subsequent physical spreading, covering, or washing. There was a shared control group of 50 male mice.