OBJECTIVE Cerebral venous sinus thrombosis (CVST) is a disease with potentially serious consequences and usually affecting young to middle aged people. This study was designed to investigate the clinical features, and predisposing and prognostic factors of CVST in a prospective series of 61 patients. METHODS This prospective study comprised 61 consecutive patients with confirmed diagnosis of CVST who were hospitalized in Namazi Hospital in Shiraz, south of Iran, between January 2000 and August 2003. The diagnosis was confirmed using conventional MRI or cerebral angiography. RESULTS The male to female ratio was 1/3.1. The mean age of patients was 35.6 +/- 12.1 years. Headache was seen in 91.8% of the patients. The most frequent risk factor was oral contraceptive consumption (62.2%). Elevation of ESR and CRP titer were seen in 37.7%, and 36.1% of patients, respectively. Involvement of superior sagittal sinus and lateral sinus was 80.3% and 41%, respectively. The final diagnosis was neurobechet in 5 ppatients (8.2%). The fatality rate was 14.7% and an altered consciousness was associated with poor prognosis. CONCLUSIONS CVST presents with a wide spectrum of symptoms and signs. Headache was the most frequent symptom. Women who used OCP were especially at risk. Because of moderate to high mortality rate, patients at increased risk of death, specially comatose patients, should be closely monitored.