Cerebral venous sinus thrombosis (CVST) is common in Asians, accounting for 15% of all strokes in the young. CVST causing malignant cerebral oedema with brain herniation and death are referred as malignant CVST. This study was aimed at evaluating the outcome of patients and factors predicting the outcome with malignant CVST after decompressive surgery. It was a retrospective, observational, single centre, hospital-based and cross-sectional study. Records of patients with malignant CVST who had decompressive surgery were analysed. Over 5 years (2010-2015), 30 patients (15 men and 15 women) underwent decompressive surgery. In univariate analysis, age more than 50 years (p = 0.05); presence of midline shift of more than 10 mm (p = 0.03) and total effacement of basal cisterns (p = 0.01) had significant correlation with poor outcome. On multivariate analysis, presence of midline shift of more than 10 mm (p = 0.01) was a significant predictor of poor outcome. Decompressive surgery is a life saving therapeutic intervention in patients with malignant CVST and more than two-thirds of patient shows favourable outcome. Age more than 50 years, midline shift >10 mm and total effacement of basal cisterns determine poor outcome following decompressive surgery.