Although ganglion cysts and stress fractures occur at many joints, the presence of both disorders at the same joint is rare. In this unusual case, a 30-year-old professional pitcher had been treated conservatively for presumed olecranon bursitis in his right (throwing) arm, but, when therapy failed, he sought additional care. A thorough workup and subsequent surgery revealed a ganglion cyst and nonunion of a stress fracture of the olecranon physis. The ganglion cyst had its origin at the fracture site, and both cyst and bone fragment were excised. The patient had a full recovery and was able to resume pitching as an instructor 18 months after surgery.