There were no specific effects for test materials on Sprague-Dawiey (S.D.) rats in clinical symptoms, amounts of food intakes, weight changes, laboratory findings, and pathology after whole body 1, 1-Dichloro-1-fluoroethane (used as coolant, metal cleaner and solvents) exposure (0, 1,500, 3,000, and 6,000 ppm) for 13 weeks (6 hour/day, 5 days/week). However, the loss of capillary vessels in eyeball (pupil) was observed in a female rat among 6,000 ppm group. Though there was a tendency for MCHC (Mean Corpuscular Hemoglobin Concentration) in rat to be decreased (p<0.05), it was not regarded as abnormal because the values were within normal limits. In asthma-stimulation related evaluations. there was also a tendency for inflammatory cell counts in bronchoalveolar lavages to be increased. But it had no statistical significance, and also no dependency on sex and the exposed concentration . Based on this result, the non observed effect level (NOEL) induced by 1, 1-Dichloro-1-fluoroethane inhalation was evaluated in groups with 3,000 ppm below (S.D. Rats, 13 weeks). Finally, it was concluded that the short term exposal of 1, 1-Dichloro-1-fluoroethane is not considered as a asthma stimulant by inhalation despite of some study limitations such as test animals use and short-term exposure.