Endemic fluorosis is a chronic disease which is caused by high intake of fluoride. Xingjing county, in Sichuan province is an area that has been believed to be endemic for fluorosis included by burning coal in which fluoride content is very high. The results of histomorphometric study showed that in some pigs, there is osteosclerosis characterized by the increased trabeculae volume while in the others, osteoporosis was found with decreased number of trabeculae and disconnected trabeculae. The observation is thought to be related to the concentration of fluoride in bone.