To the Editor: The study by Geerts et al. (Dec. 15 issue)1 emphasizes once again the substantial incidence of thromboembolism after major trauma. We were surprised, however, that such a prospective study was undertaken in a group of high-risk patients and that no prophylaxis against thromboembolism was used. As the authors themselves have noted, high rates of deep-vein thrombosis in patients with multiple trauma have been described previously.2 The National Institutes of Health Consensus Development Conference also recognized this fact and recommended prophylaxis for such patients three years before Geerts et al. started their prospective study.3 Why was no prophylaxis.