Ganglion cyst is the most common benign tumor arising from the hand and wrist. Rarely, they are found within the tendon. To date, only 10 cases in English papers and 7 cases in domestic papers on ganglion cysts in extensor digitorum tendons have been reported. Due to the rarity of this entity, it is difficult to suspect intratendinous ganglion fully based on the physical examination. Accordingly, preoperative studies such as ultrasonography, magnetic resonance imaging are recommended when suspicious result is revealed on the physical examination. Treatment should include en bloc resection of the affected tendon to reduce recurrence. But functional loss always has to be considered. This study reports two cases of intratendinous ganglion cysts that arised from the second and fourth extensor digitorum tendon.