Capillarioscopy has been unjustifiably neglected in the study of connective tissue diseases, where examination of the microcirculation is clearly important. A study of 80 cases is reported. 12 systemic lupus, 11 progressive systemic sclerosis (PSS), 20 rheumatoid arthritis (including 3 juvenile and 2 Still's disease); 9 Raynaud's disease (of which 3 idiopathic, 4 with rheumatoid arthritis and 2 with UCTD); 1 dermatomyositis; 11 other CTD (2 overlap syndrome--1 lupus + dermatomyositis; 1 lupus + PSS--3 Sjögren syndromes with rheumatoid arthritis, 1 MCTD, 2 primary mixed cryoglobulinaemia, 1 systemic vasculitis, 1 Behçet syndrome, and 1 UCTD); 9 miscellaneous forms (3 psoriatic arthropathy, 1 rheumatic pelvispondylitis, 1 allergic dermatitis, 1 pulmonary TB, 1 ulcerative colitis; 1 scapulohumeral periarthritis, 1 unclassifiable rheumatism; 7 healthy subjects). During capillarioscopy, from one to nine slides were prepared for each subject. These were interpreted separately by three persons who were unaware of the respective diagnosis. Calibre, tortuosity, length and number of capillaries were recorded, plus the visibility of the subpapillar plexus, height and number of the termal, subungual and/or ungual vallum haemorrhage, plugging. It was found that PSS, dermatomyositis, MCTD, and overlap-PSS revealed a very typical common pattern, possibly pathognomonic, namely marked reduction in the number of capillaries + megacapillaries. The other forms presented less evocative diagnostic patterns, though they were fairly indicative in some instances. Clinical correlations of particular significance with respect to prognosis, however, were not observed.