Objective To analyse the association between the Glasgow Coma Scale (GCS) score at intensive care unit (ICU) discharge and the 1-year outcome of patients with severe traumatic brain injury (TBI). Design Retrospective analysis of prospectively collected observational data. Patients Between 01/2001 and 12/2005, 13 European centres enrolled 1,172 patients with severe TBI. Data on accident, treatment and outcomes were collected. According to the GCS score at ICU discharge, survivors were classified into four groups: GCS scores 3–6, 7–9, 10–12 and 13–15. Using the Glasgow Outcome Scale (GOS), 1-year outcomes were classified as “favourable” (scores 5, 4) or “unfavourable” (scores <4). Factors that may have contributed to outcomes were compared between groups and for favourable versus unfavourable outcomes within each group. Main results Of the 538 patients analysed, 308 (57 %) had GCS scores 13–15, 101 (19 %) had scores 10–12, 46 (9 %) had scores 7–9 and 83 (15 %) had scores 3–6 at ICU discharge. Factors significantly associated with these GCS scores included age, severity of trauma, neurological status (GCS, pupils) at admission and patency of the basal cisterns on the first computed tomography (CT) scan. Favourable outcome was achieved in 74 % of all patients; the rates were significantly different between GCS groups (93, 83, 37 and 10 %, respectively). Within each of the GCS groups, significant differences regarding age and trauma severity were found between patients with favourable versus unfavourable outcomes; neurological status at admission and CT findings were not relevant. Conclusion The GCS score at ICU discharge is a good predictor of 1-year outcome. Patients with a GCS score <10 at ICU discharge have a poor chance of favourable outcome.