There were no specific effects for test materials on Sprague- Dawley (S.D.) rats in clinical symptoms, amounts of food intakes, weight changes, laboratory findings, and pathology after whole body 1,I-DichloroI-fluoroethane (used as coolant, metal cleaner and solvents) exposure(U, 1,500, 3,000, and 6,000 ppm) for I3 weeks (6 hour/day, 5 days/week). However. the loss of capiIlary 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, I3 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.