BACKGROUND: Elevated serum alanine aminotransferase (ALT) as a marker for diagnosis, and assessment of severity in patients with blunt hepatic injuries are hitherto un-described or casually mentioned in literature. METHODS: Prospective observational study of all patients admitted with blunt abdominal trauma accrued between May 2002 and December 2003. Upon admission, vital parameters were recorded and blood samples were drawn for haemogram and serum ALT (SGPT) levels. Patients were further evaluated with USG, CT scan or underwent a laparotomy. RESULTS: Of the 122 patients with blunt abdominal injury, 32 had raised ALT, among these 31 had liver injury. No patient with a normal ALT had hepatic injury. Five patients with a significantly raised ALT and negative USG had liver injury. Patients with modestly raised ALT, mostly resolved on non-operative treatment, whereas, patients with more marked rise had more serious hepatic injuries, more complications, greater transfusion requirement, and higher death rates. CONCLUSION: This observational cohort study strongly suggests that raised serum ALT is a sensitive diagnostic marker for blunt liver injury and its levels may assist with prognosis and guide management.