INTRODUCTION The objective of this study was to determine the toxicity of a selected petroleum-derived hydrocarbon@ API 83-20@ when administered to rabbits over a 4-week period by dermal application. The test article was evaluated in two (2) separate studies. The initial study. Project 17140 (2)@ was conducted at dose levels of 0@ 108@ 540@ and 1080 mg/kg whereas the second study. Project 85023(2)@ was conducted separately at dose levels of 0 and 2000 mg/kg. Results of both studies are reported herein. In the initial study@ dosing was initiated on April 15@ 1985 and was completed by May 14@ 1985. In the second study@ dosing was initiated on June 2@ 1986 and completed on June 28@ 1986. All animals were terminated by T-61R euthanasia solution. A pilot five-day dermal study in rabbits (Phase 1) was performed in order to determine the dose levels to be used during this study (Phase II). Phase I dosing was initiated March 4@ 1985 and was completed on March 8@ 1985. Terminal sacrifice occurred on March 15@ 1985. The report of the Phase I study is presented in Addendum I of this report.