The Glasgow Aneurysm Score (GAS), developed and published by the same authors, is a clinical prognostic scoring system that predicts mortality when operating on either intact or ruptured abdominal aortic aneurysms (AAA) taking into account these clinical criteria: patient's age, shock at presentation, myocardial disease, cerebrovascular disease and renal disease. The GAS was prospectively evaluated by studying 320 consecutive patients with AAA who were operated on at Glasgow, Aberdeen and Inverness, Scotland, in the period between January 1990 and May 1993. Logistic regression analysis showed very similar results to the original analysis used in developing the score. Age, shock, myocardial disease and renal disease were highly significant. Although it was not significant, cerebrovascular disease weight was not significantly different to its value in the original analysis. The mortality correlated well with the values of the score and ranged from 0% for scores below '70 GAS' to 80% for scores over '95 GAS'. The GAS appears, therefore, to be a reliable clinical predicative tool in foretelling the outcome of operating on AAA in terms of operative in-hospital mortality.