Objective To study the effects of sand therapy on the ultrastructure of knee articular cartilage in rabbits with osteoarthritis ( OA ) and provide evidence of the effectiveness of sand therapy for OA in Uyghur medicine. Methods Models of knee OA were established by fixing with gypsum the right hind limbs of 28 rabbits. Of these, twenty-six rabbits were divided randomly into a free movement group and a free movement plus sand therapy group, and their left hind limbs were used as normal controls. Another two rabbits were used as specimens. The thirteen rabbits in the free movement group after the gypsum fixings were removed were allowed free movement every day for 20 days; the thirteen rabbits in the free movement plus sand therapy group had free movement plus sand therapy every day. The ultrastructure of each rabbit' s knee articular cartilage was observed using an electron microscope. Results Models of knee OA were established successfully. The changes in the ultrastructure of the knee articular cartilage revealed cell swelling, cell debris in part of the cartilage lacunae, and cartilage cells proliferating. The matrix of cartilage cells was thin, hetero chromatin concentrated on the margin and presented in a crescent form. Cell organellae decreased obviously, which was a sign of apoptosis. After the gypsum fixings were removed, the proliferation of cartilage cells gradually increased and rough endoplasmic reticula increased remarkably in the articular cartilages of the right hind knees of the free movement group. Cell pycnosis, disintegration and necrosis could be found in a few cells. The movement of the affected knees of the group treated with sand therapy plus free movement improved more significantly , and the changes in cartilage ultrastructure revealed more cell active proliferation, more rough endoplasmic reticu-lum, more cell surface processes and more matrix fibers. The morphology of cartilage cells in the control knees remained normal. Conclusion It is confirmed that Uyghur sand therapy combined with movement can improve the ultrastructure of knee articular cartilage in a rabbit model of OA.