Since seat belt legislation was introduced in this country in 1983, we have seen an increasing number of patients admitted to our unit for observation following seat belt related sternal fractures. In order to determine the value of routine admission of patients with isolated sternal fracture we have reviewed a series of 104 consecutive patients admitted between February 1983 and February 1990 with this injury. Of these, 90 were sustained in road accidents, 79 of which were as a consequence of seat belt use. The average age of these patients was 54.5 years (range 11-85 years) with an average duration of hospital stay of 2.9 nights. No serious complications were observed. These findings suggest that there may be no need to admit these patients solely for observation if their initial clinical condition is satisfactory and there are no abnormalities identified by an anteroposterior chest radiograph and electrocardiography.