A hemangioma in the knee joint of a 37-year-old woman was diagnosed by magnetic resonance imaging. The case presented with pain and a tender localized swelling lateral to the patellar tendon. Arthroscopy verified the diagnosis but did not allow visualization of the full extent of the tumor. After arthroscopic subtotal excision of the associated hypertrophic medial plica, a miniarthrotomy was done. The tumor was attached to the periphery of the anterior horn of the lateral meniscus, to the anterior tibial plateau, and to the fat pad. It seemed to take its origin from the venous plexus just below the anterior lip of the central tibial plateau. The patient was asymptomatic 9 months after surgery. In hemangiomas not amenable to arthroscopic surgery, open excision through miniarthrotomy ensures complete removal without prolonging recovery.