The clinical and laboratory features of 32 patients with anti-PM-Scl were studied. Patients with this rare autoantibody suffered from a homogenous overlap connective tissue disease defined by Raynaud phenomenon (32/32), features of scleroderma (31/32), arthritis (31/32, erosive in 9/32), myositis (28/32), lung restriction (25/32), calcinosis (15/32), and sicca (11/32). Significant renal and neurologic involvement was uncommon. All patients examined (22/22) had HLA-DR3, and 50% of these patients were homozygous. Our patients responded favorably to moderate immunosuppression and, with therapy, the disease generally has a good prognosis; over 50% of our series (17/32) remained well on minimal or no immunosuppression after a median follow-up of 8 years.