INTRODUCTION The objective of this study was to determine the nephrotoxic potential to male rats of selected hydrocarbon materials when administered neat by oral intubation five days per week over a four-week period. Each material was administered at 0.5 and 2.0 g/kg. The study was conducted in three phases. Phase I was initiated on June 2@ 1983 and terminated on June 29@ 1983; Phase II was initiated on July 20@ 1983 and terminated on August 16@ 1983: and Phase II I was initiated on March 21@ 1984 and terminated on April 17@ 1984. Each phase had a control group that was dosed with isotonic1c saline at a dose level of 2.0 g/kg. In addition. for each phase API PS-6- Fuel was dosed at 0.5 and 2.0 g/kg and served as a reference control.