Thirteen trauma patients admitted to a major injuries unit were classified according to their injury severity. Urinary excretion of total protein, albumin and gamma glutamyl transpeptidase (GGT) activity were assessed over the following 6 days. All patients showed an initial glomerular and tubular proteinuria during the first 24 h which subsided by the second post-trauma day. The excretion of total protein and albumin was positively correlated with injury severity. Those patients with the severest injuries showed a marked recurrent total proteinuria around days 3 to 4 post-trauma which exhibited features of a tubular lesion. The recurrent proteinuria peak coincided with peak levels of serum c-reactive protein (CRP).