The combination of a large range of motion and insufficient bony stabilization makes the glenohumeral joint susceptible to injuries including dislocation in young athletes. Magnetic resonance arthrography (MR-arthrography) and computed tomography arthrography (CT-arthrography) play an important role in the preoperative workup of labroligametous injuries. This paper illustrates MR-arthrography and CT-arthrography findings acquired at the same time on the same subjects to illustrate common causes and sequelae of shoulder instability. Teaching Points . MR-arthrography and CT-arthrography are equivalent for SLAP and full-thickness rotator cuff tears. . CT-arthrography is superior in evaluating osseous defects and cartilage surface lesions. . MR-arthrography is superior in evaluating intrasubstance and extra-articular tendinous injuries.