Background: Although surgical decompression of large hemispheric infarction is often a life-saving procedure, many patients remain functionally dependent. The aims of this study were to identify specific factors that can be used to predict functional outcome, thus establish predictive criteria to reduce poor surgical results., Method: In this non-randomized prospective study, we performed decompressive craniectomy in 32 patients (age range, 27 to 77 years) with large hemispheric infarctions. Based on their modified Rankin Score (RS), which was calculated 6 months postoperatively, patients were divided into two functional groups: good (RS 0-3, n = 7) and poor (RS 4-6, n = 25). The characteristics of the two groups were compared using statistical analysis., Findings: One-month mortality was 31%. However, most of the surviving patients were severely disabled (RS 4 or 5), and 6-month total mortality reached 50%. Increased age (> or = 60 years) (P = 0.010), preoperative midline shift greater than 10 mm (P = 0.008), low preoperative Glasgow Coma Score (GCS < or = 7) (P = 0.002), presence of preoperative anisocoria (P = 0.032), early (within the first three days of the stroke) clinical deterioration (P = 0.032), and an internal carotid artery infarct (P = 0.069) were the positive predictors of a poor outcome., Interpretation: We view decompressive craniectomy for space-occupying large hemispheric infarction as a life-sparing procedure that sometimes yields good functional outcomes. A dominant hemispheric infarction should not be an exclusion criterion when deciding to perform this operation. Early operation and careful patient selection based on the above-mentioned factors may improve the functional outcome of surgical management for large hemispheric infarction.