Achloric algae of the Prototheca species are a rare cause of infection in humans. These infections are usually localized to the skin, olecranon bursae, and tendon sheaths of the hands and wrists. Our patient with acquired immunodeficiency syndrome and a chronic Prototheca wickerhamii skin infection of the hand developed tenosynovitis and arthritis of his ankle in the setting of a documented algemia. This is the first reported case of protothecal arthritis and tenosynovitis resulting from hematogenous dissemination. The reported musculoskeletal manifestations of protothecal infections are reviewed.