Fischer 344 rats (10/sex/exposure concentration) and New Zealand White rabbits (7/sex/exposure concentration) were exposed to 0, 300, 1000, or 3000 ppm (0, 1.09, 3.62, or 10.9 mg/L) of propylene glycol monomethyl ether (PGME) for 6 hr/da, 5 da/wk, for 13 weeks. Minimal effects were observed in animals exposed to 3000 ppm. Indications of a transient central nervous system depression were observed in rats and rabbits exposed to 3000 ppm. There were also small increases (6 to 8%) in mean relative liver weights of 3000 ppm exposed male and female rats relative to controls. Minimal histologic effects were observed in the livers of 3000 ppm exposed female rats. These were suggestive of hepatocellular hypertrophy but were without evidence of degenerative changes. There was an increase in the urinary pH of male rats exposed to 3000 ppm PGME for 4 weeks, but this was not evident after 12 weeks of exposure. There was no indication of histopathological effects in the kidneys of either species, and there were no hematological effects. No treatment-related effects were found in either rats or rabbits exposed to 300 or 1000 ppm.