Forty-four study patients with scleroderma (systemic sclerosis) (28 patients), Raynaud's syndrome (13 patients) or dermatomyositis (three patients) were observed for skin capillary abnormalities by widefield microscopy and compared with three control groups of 20 subjects each: (1) patients with other rheumatic disease, (2) hospitalized patients with nonrheumatic conditions, and (3) healthy volunteers. The distinctive microvascular pattern (dilated and distorted capillary loops alternating with avascular areas) previously reported in scleroderma and dermatomyositis was observed almost exclusively in the study patients. The severity of capillary abnormalities varied among the diagnostic subgroups, and a positive correlation was found between the degree and extent of abnormal microvascular patterns and multisystem involvement. On this basis, widefield nailfold capillary observations are proposed as a simple, inexpensive, reproducible technic for making an improved early diagnosis and predicting multisystem involvement in scleroderma, Raynaud's syndrome and dermatomyositis, presently a group of loosely associated and overlapping connective tissue disorders which often defy early and precise diagnosis.