Purpose: To compare thirst, drinking behaviour, and en-dothelin-1 (ET-1) pl asma levels between vasospastic and non-vasospastic subjects. Methods: We compa red 67 subjects with a primary vasospastic syndrome with 64 age-and sex-matche d non-vasospastic control subjects. A detailed medical history was recorded, in cluding a questionnaire containing queries about thirst and drinking behaviour, history of migraine or unspecific headache, history of episodes of low blood pre ssure, and smoking habits. Body mass index (BMI) was calculated and blood sample s were drawn for ET-1 measurements. Results: Subjects with a vasospastic syndro me reported a reduced desire to drink and a lower estimated quantity of daily fl uid intake, more often forgot to drink, more often had both migraine and unspeci fic headache, more often had episodes of low blood pressure, and had an increase d plasma level of ET-1. These features differed statistically significantly bet ween the two groups. There was also a non-significant trend among vasospastic s ubjects to smoke less and to have a smaller BMI. Conclusion: A reduced desire to drink is found frequently among vasospastic subjects. Methods: To compare thirst, drinking behavior, and en-dothelin-1 (ET-1) pl as ma levels between vasospastic and non-vasospastic subjects. Methods: We compa red 67 subjects with a primary vasospastic syndrome with 64 age-and sex- A detailed medical history was recorded, in cluding a questionnaire containing queries about thirst and drinking behavior, history of migraine or unspecific headache, history of episodes of low blood pre ssure, and smoking habits. Body mass index Results: Subjects with a vasospastic syndro me reported a reduced desire to drink and a lower estimated quantity of daily fl uid intake, more often forgot to drink, more often (BMI) was calculated and blood sample s were drawn for ET-1 measurements. had both migraine and unspeci fic headache, more often had episodes of low blood pressure, and had an increase d plasma level of ET-1. These features differed statistically significant bet ween the two groups. n-significant trend among vasospastic s ubjects to smoke less and to have a smaller BMI. Conclusion: A reduced desire to drink is found frequently among vasospastic subjects.