We use the term Raynaud Phenomenon (RP) to define episodic digital ischemia with colour changes involving the digits of the hands and feet, induced by cold or emotional stresses. Surprisingly little information is available concerning the incidence of RP in the general population. In Italy, studies of this purpose have never been carried out and the few investigations, we find in literature, are discording, showing an incidence between 0.83% and 27%. The interest in knowing the incidence of RP is, beside the usual reason which get to an epidemiological study, RP indeed may be associated with severe and disabling clinical conditions as connective tissue diseases. The RP may be the initial complaint on an otherwise silent systemic illness and may even influence the course of these clinical conditions, assuming the role of prognostic index. It seemed useful for us to investigate on a model of population resident in our city the incidence of RP and the frequency of the idiopathic and secondaries forms. We have prepared a set of questions which was distributed to some students attending the IV year of the School of Medicine and to specialized doctors. The students randomly interviewed as many people as they could, while the doctors had to fill the questionnaire for companions of patients coming to three different Sanitary Units in Milan. All those subjects that at first instance were diagnosed as RP were sent to our ambulatory where more experienced doctors provided to collect a precise history.(ABSTRACT TRUNCATED AT 250 WORDS)