Some foot and ankle pathologic conditions can be treated by an endoscopic approach. Its effectiveness has been reported in the treatment of plantar fasciitis. The authors have used an endoscopic approach in the treatment of posterior tibial tenosynovitis resistant to nonsurgical treatment. A review of the pathology, terminology and the diagnosis of tenosynovitis is provided. The case report demonstrates a technique using an endoscope to incise the posterior tibial tendon sheath.