Raynauds syndrome, acrocyanosis and erythromelalgia are functional vascular diseases that differ with respect to prevalence, clinical picture, therapy, prognosis, and impairment of quality of life. Raynauds syndrome occurs in 5 to 20 % of the population in Europe, is observed four times more often in women than in men and appears first at the age of 40 (3 to 80), on the average. Raynauds attacks are characterized by a paroxysmal white-blue-red or just white and blue discoloration of the fingers and toes; the attacks are induced by cold or stress, usually, cease after no more than some minutes (average 23 min.), but can also persist for hours. A distinction must be made between primary (aetiology unknown), secondary (aetiology known) and suspected secondary Raynauds syndromes (causal underlying disease suspected). There are several different therapy options, but not all of them have been substantiated by evidence. Acrocyanosis is rarer than Raynauds syndrome, and contrary to the latter, is characterized by nonparoxysmal, in most cases persistent, painless bluish-red symmetrical discolorations of the hands, feet and knees. It is more frequent in women than in men and becomes manifest before the 25th year of age, on the average (15th to 70th year of age). A distinction is made between primary acrocyanosis without detectable underlying disease and secondary acrocyanosis with a specific underlying disease. No effective therapy for primary acrocyanosis is known, but secondary forms can sometimes be treated. Patients with primary and secondary erythromelalgia, a very rare condition, sustain paroxysmal burning pain with marked reddening of the legs, feet and less often the hands. The attacks are triggered by warmth. Women are affected more often than men. The age of first manifestation is 40 to 55 years, but the first attacks may just as well occur during childhood. There are different therapeutic approaches with occasional success, but no general recommendations.