We revised the clinical files of 326 patients who underwent nailfold capillaroscopy. These patients could be subdivided into 4 groups: I: patients with clinical suspicion of connective tissue disease, II: patients with isolated Raynaud's phenomenon, III: patients with existing connective tissue disease, IV: patients with acrocyanosis, chronic pernio or related disorders. The presence of megacapillaries was noted. The sensitivity of their presence for the various categories of connective tissue disease was as follows: systemic sclerosis (n = 11): 100%, CREST (n = 15): 73%, MCTD (n = 9): 56%, dermatomyositis (n = 7): 86%. Nineteen patients with megacapillaries had no final diagnosis of connective tissue disease (specificity 93.3%). The positive predictive value of the presence of megacapillaries for a scleroderma spectrum disorder (SSD) was 63.5% and the negative predictive value of a normal capillaroscopy 96.7%. We conclude that nailfold capillaroscopy can be advised to rule out SSD's.