1. Biochemical changes in male, Wistar rats, treated with different doses of 1,2-dichloropropane (50-500 mg kg-1 body weight), were investigated at the end of a 4-week treatment and after a 4-week recovery period. 2. The behaviour of Phase I and Phase II metabolic steps and of the angiotensin converting enzyme activity of the renal proximal tubule brush border were determined. 3. Phase II is more affected by the solvent than Phase I metabolism, and liver metabolism is more affected than the kidney. 4. Angiotensin converting enzyme activity from the proximal tubule brush border appears to be the most sensitive parameter of kidney involvement during treatment. 5. After a 4-week recovery period all the metabolic indices together with angiotensin converting enzyme activity have returned to normal. Only liver reduced glutathione content shows a slight, but significant, increase for the highest dose (500 mg kg-1 body weight). 6. The results show that the biochemical changes induced in liver and kidney by 1,2-dichloropropane are reversible.