The Glasgow Coma Scale (GCS) is the most universally accepted system for grading level of consciousness. Predicting outcome is particularly difficult in poor grade aneurysmal subarachnoid haemorrhage (aSAH) patients. We hypothesised that the GCS and individual examination components would correlate with long-term outcome and have varying prognostic value depending on assessment time points. GCS scores of 160 aSAH patients presenting in stupor or coma were prospectively recorded on admission and each subsequent day until hospital day 14. Early treatment was planned for each patient unless the patient’s family refused aggressive intervention or the patient died before surgery. Outcomes were assessed by the modified Rankin scale (mRS) at 14 days, 3 months, and one year.