Acute calcific tendinitis is a frequently unrecognized cause of hand and wrist tenderness and swelling. We report 12 cases seen over an 8-year period. Roentgenograms showed deposits in various peritendinous sites especially near the pisiform. Special views may be required for visualization. A correct diagnosis was made in 5/12 cases; other etiologies considered included closed-space infections. In most cases, treatment consisted of immobilization plus nonsteroidal antiinflammatory drugs or local steroid injections. Results were uniformly good. Seven of 7 patients demonstrated resolution of calcium deposits on subsequent roentgenograms. Failure to recognize this entity may cause unnecessary investigation and therapy.