The Guizhou semi-fine sheep in the Weining County, Guizhou province, south west China karst mountain area were affected by an ailment characterized by pica, emaciation, dyskinesia, depressed appetites, unsteady gait and anemia. We found that concentrations of copper (Cu) in soil and forage from affected and unaffected areas were within the normal ranges, but concentrations of sulfur (S) and molybdenum (Mo) in soil and forage were significantly higher (P<0.01) in affected areas than in unaffected areas. Concentrations of Cu in blood, wool and liver from the affected Guizhou semi-fine sheep were significantly lower (P<0.01) than those in healthy animals. Affected Guizhou semi-fine sheep showed a hypochromic microcytic anemia and a low level of ceruloplasmin. Oral administration of CuSO4 prevented and cured the disease. We conclude that the disorder of Guizhou semi-fine sheep is caused by secondary Cu deficiency, mainly due to high S and Mo content in forage.Key words: Guizhou semi-fine sheep, copper, sulfur; molybdenum, South west China karst mountain area.