Protothecosis is a rare infection caused by achlorophyllic algae called Prototheca. Approximately 117 cases have been described in the literature world wide, the majority caused by the species P. wickerhamii. Cutaneous infection is the most common and cases of tenosynovitis are very rare. A local or systemic immunosuppressive factor is seen in half of the cases of protothecosis. We report a case of protothecal tenosynovitis in a middle-aged, immunocompetent woman that developed after she received sclerosing therapy of varicose veins. Administration of itraconazole with surgical débridement produced a good response. We also review the published cases of protothecal tenosynovitis.