To determine the prevalence of Raynaud's phenomenon (RP) in Spain, we studied a working population of 988 men and 479 women. The overall prevalence of RP was 3.7%, with a 3.2% rate for men and 4.7% for women. There was a statistically significant association between Raynaud's phenomenon and a personal or familial history of perniosis, acrocyanosis or migraine among women. The age at onset was significantly lower in women. RP was classified as primary in 89% of the cases and as secondary in 11%. Examination by capillaroscopy revealed no significant differences between primary Raynaud cases and controls.