Skeletal muscle involvement may occur at all stages of HIV infection. The most simple classification of muscular disorders in HIV-infected patients is 1) HIV-associated myopathies, 2) zidovudine myopathy, 3) HIV wasting syndrome, and 4) opportunistic infections and tumoral infiltrations of muscle. Immunohistology for major histocompatibility complex class I antigen and histochemical reaction for cytochrome c oxidase are helpful in correctly classifying a myopathy as HIV polymyositis or zidovudine myopathy. Studies of cytokine expression in HIV-infected patients and of supplementation with compounds such as carnitine or micronutrients such as selenium might yield new insights into the pathogenesis and treatment of the various AIDS-associated muscular disorders.