ABSTRACT The test material API #78-3@ #2 Home Heating Oil (10% Cat)@ was tested for potential acute toxicity@ using a battery of six tests: Primary Skin Irritation@ Primary Eye Irritation@ Skin Sensitization@ Acute Dermal Toxicity@ Acute Oral Toxicity@ and Subacute Dermal Toxicity. Materials@ methods@ and results of individual tests are presented in this report. The test material API #78-3 produced moderately irritating primary skin effects. The acute dermal test resulted in skin irritation but not systemic toxicity. Subacute dermal testing produced acute dermal corrosion at all three dosage levels; histopathologic examination of tissues confirmed dermal toxicity at all dosage levels and indicated hepatic toxicity at the 10 ml/kg dosage level. The oral median lethal dose@ i.e.@ oral LD50@ of the test material is 14.5 ml/kg. The test material can be considered mildly irritating for primary eye irritation. Results of the skin sensitization test indicate that API #78-3 is non-sensitizing.