Intratendinous ganglions are rare types of ganglions arising from the substance of a tendon. They are difficult to diagnose as they are usually asymptomatic unless they attain a large size. Here, we present a case of an intratendinous ganglion of the extensor digitorum communis tendon of the right ring finger, causing a swelling on the dorsal aspect of the distal forearm. It was confirmed with an ultrasound and was surgically excised and the tendon was reconstructed with a palmaris longus tendon graft. Post–operative was uneventful and this case was presented due to the rarity of the disease.