Atypical mycobacterium infections caused by Mycobacterium fortuitum have been increasing. Although it was once considered a saprophytic organism, M. fortuitum has been documented to cause infections in humans. The diagnosis and treatment of these infections often requires a multidisciplinary approach. The mainstay of treatment consists of prolonged antibiotic therapy and thorough surgical debridement of the infected site. M. fortuitum was the cause of infection at the right popliteal fossa in a 69-year-old woman who was receiving steroid injections for a painful Baker's cyst.