Pseudogout, defined as recurrent acute arthritis due to intrasynovial deposition of calcium pyrophosphate dihydrate crystals, is a relatively common arthritic disorder of the elderly. The clinical and roentgenographic aspects of 50 cases of pseudogout in hospitalized patients are reviewed in this paper. Oligoarticular and polyarticular episodes were observed in half of these patients. Antecedent problems included infection, trauma, surgery and vascular events. Consistent with previous reports, most patients had roentgenographic evidence of chondrocalcinosis. A third had asymptomatic capsular or periarticular calcific deposits or both, and a third had pyrophosphate arthropathy, a progressive, destructive, accelerated form of osteoarthritis. An attack of pseudogout may offer a clue to the presence of an unsuspected metabolic disease, such as primary hyperparathyroidism or idiopathic hemochromatosis.