Fluid extravasation is not uncommon after shoulder arthroscopy. We report a case of massive fluid extravasation that resulted in rhabdomyolysis and renal shutdown following routine shoulder arthroscopic surgery. Compartment pressures in the deltoid, supraspinatus, and infraspinatus were normal. Magnetic resonance imaging of the shoulder revealed extensive subcutaneous edema and high-signal changes in the entire deltoid muscle. The patient made an uneventful recovery with adequate supportive treatment and renal dialysis. Repeat imaging studies 3 months later revealed complete restoration to normal of the deltoid muscle. In addition to extensive fluid extravasation in this patient, the use of nonsteroidal anti-inflammatory medication, the development of a transient allergic reaction to a prescribed antibiotic, and the inclusion of epinephrine in the infusion fluid may have collectively contributed to rhabdomyolysis. We recommend that the use of infusion pumps should be limited to the shortest time possible, and that gravity inflow should be used as much as possible. Inflow should preferably occur through the arthroscope itself, rather than through a separate portal cannula, which may dislodge, inadvertently causing infusion of high-pressure fluid into the surrounding tissue.