Groups of 10 male CelacD(SD)BR rate were exposed to either 0.11, 0.60 or 3.1 mg/L of isooctanol in air. Exposures were 6 hours/day, 5 daya/week for 2 weeks. A control group was simultaneously exposed to air. At the end of the exposure period and after a 14-day recovery period, blood and urine samples were collected for clinical analysis and rate wer6 sacrificed for pathological examination. Clinical signs of toxicity observed during the exposure phase included lung noise in a few rats exposed to 0.11 or 0.60 mg/L. Rats exposed to 3.1 mg/L exhibited lung no1ae, neeal and ocular discharges, red-stained perineum, inactivity, impaired balance, ruffled fur, and alopecia. High level rats also had a significantly lower group mean body weight compared to controls from test day 2 throughout the study. Clinical pathology measurements made at the end of the exposure and recovery periods showed no compound-related differences between control rats and rats exposed to 0.11 ag/L. Rata exposed to 0.60 or 3.1 ag/L showed significant increases in red blood cell-parameters which were interpreted to be evidence of treatment-related polycythemia. Rats from the 3.1 ag/L.group also showed significant decreases in white blood cell counts and absolute numbers of lymphocytes which were interpreted to be evidence of physiologic stress with endogenous steroid release. Other homatologic and clinical chemical differences were interpreted to be within the range of expected biological variation. None of these treatment-related effects were present after a 14-day recovery.