The HLA phenotype frequencies of 40 patients with progressive systemic sclerosis (PSS) and 42 patients with morphea (sclerodermia circumscripta) indicate a weak, HLA-linked genetic predisposition of the affected individuals (70 female, 12 male). An "opposite" HLA A1, B8 (high immune response) vs A3, B7, DR2 (low immune response) constellation in PSS and morphea supports the clinical subdivision of scleroderma into these different nosological entities, and may serve as a differential diagnostic tool and prognostic marker.