A multicentre observational study was conducted in order to detect the major clinical diagnosis found in 761 patients with Raynaud's phenomenon (RP) attending 50 Italian centres for rheumatology and internal medicine. Systemic sclerosis was the most frequent condition associated with secondary RP, occurring in 216 (28.4%) patients. The other most frequent clinical diagnoses included systemic lupus erythematosus (52 cases: 6.8%) and rheumatoid arthritis (38 cases: 5%). Other RP-related diseases (hypertension, Sjögren's syndrome, mixed connective tissue disease, undifferentiated connective tissue disease, fibromyalgia, carpal tunnel syndrome, cryoglobulinemia, dermatopolymyositis, vasculitis, thoracic outlet syndrome, hypothyroidism, diabetes mellitus) occurred in less than 5% of cases. A total of 130 (48%) out of 268 patients with primary RP showed one or more clinical features indicating a fairly high risk of evolving into fully established systemic sclerosis. None of these patients fulfilled the ACR criteria for systemic sclerosis. This study shows that over 50% of patients with RP attending 50 Italian centres for rheumatology and internal medicine had a connective tissue disease. The large number of patients with primary RP and isolated clinical features of connective tissue disease indicates that more efforts should be focused on developing new criteria for the classification of RP.