Two patients with clinical and pathologic features of eosinophilic fasciitis manifested serologic and systemic abnormalities that raised the question of the fundamental nature and relationship of eosinophilic fasciitis to scleroderma. In addition to the characteristic features of eosinophilic fasciitis, both patients exhibited arthritis, a predominantly mononuclear cell infiltration of muscles with normal serum muscle enzyme levels, weakly positive serum antinuclear factor, IgA deficiency, and abnormalities of pulmonary function. In addition, one patient had wide-mouthed colonic diverticulae and synovial deposits consistent with amyloid; the second patient had bone marrow hypoplasia. Although corticosteroid therapy was of benefit, hydroxychloroquine and potassium para-aminobenzoate were of further help in controlling the disorder. Biopsies from the two patients revealed inflammatory lesions to be heaviest deep in the skeletal muscle; fascia was only minimally inflamed with mild fibrosis. The findings suggest that striking fibroinflammatory lesions noted in the fascia in some patients with eosinophilic fasciitis may derive largely from spillover of lesions in neighboring skeletal muscle.