This paper reports the relation between fluoride contents and pathologic changes of skeletal system in Wistar rats after inhalation of organofluoride compound-trifluoromethyl hypofluoride. The trifluoromethyl hypofluoride (CF3OF), purity greater than 95%, used in this study was produced and provided by the Chenguang Chemical Industrial Institute. Twenty-four Wistar rats, weighing between 200 and 250g, were divided into three groups: a control group and two test groups. They were exposure to the trifluoromethyl hypofluoride gas at a dosage of 0, 0.067 and 0.1 ppm respectively, in 1 m3 Plexiglass chamber, two hours a day, five days a week. The results showed that the fluoride levels of ilia in 0.067 and 0.1 ppm group rats were significantly higher than those in the control group (P less than 0.05). The osteogenic effect of CF3OF was confirmed by the histopathological examination of the skeletal tissues. The lesions were also mainly limited to the 0.1 ppm CF3OF group. A very marked osteogenic reaction was found in the periosteum and Haversian canals of ilia in the rats including focal active periosteous osteoblastic proliferations and bone or osteoid tissues forming with a little osteoclastic reactions. for 23 weeks.