OBJECTIVE: The aim of this study was to examine the relationship between body mass index and clinical features of headaches in patients with primary headaches and to consider the impact of body mass index on quality of life related to the health of patients with primary headaches. STUDY DESIGN: This is a cross-sectional study. PARTICIPANTS AND METHODS: The study involved 30 patients suffering from primary headache at the Headache Clinic of the Clinic of Neurology, University Hospital Center Osijek. An anonymous questionnaire structured for this study and a standardized SF-36 (Short Form Health Survey) questionnaire to assess quality of life related to health were used as instruments for this study. RESULTS: In patients with primary headaches, 14 (47 %) patients are overweight or obese. There is no significant correlation between the demographic characteristics and the BMI of the respondents, except that the frequency of overweight or obesity is higher in employed patients (P = 0.007). An association between the frequency of primary headaches and elevated body mass index (P = 0.04) was observed. There is no significant association between other clinical features of primary headaches and body mass index. There are no significant differences in health-related quality of life relative to body mass index. CONCLUSION: The presence of overweight and obese individuals is relatively high in the population with primary headaches (migraine and tension headaches) according to the measured body mass index. Patients with primary headaches who are overweight or obese have significantly more frequent headache attacks compared to normal-weight and malnourished patients. There is no significant association between other clinical features of primary headaches (type, severity and duration of attacks, therapy) and body mass index. There are no significant differences in health-related quality of life relative to body mass index.