A 27-year-old woman without known risk factors contracted HIV and was given highly active antiretroviral therapy in 2006. She subsequently developed myasthenia gravis (MG) that responded to treatment with pyridostigmine bromide and azathioprine. The medical literature, consisting primarily of case reports, indicates that MG occurs in relatively immunocompetent HIV-infected persons who generally present with mild MG symptoms. As such, we recommend a high index of suspicion for MG in HIV-infected patients presenting with fatigue and weakness, especially those receiving highly active antiretroviral therapy.