In adults, mild traumatic brain injury (MTBI) frequently results in impairments of cognitive functions which would lead to psychological consequences in the future. Cerebrolysin is a nootropic drug, and can significantly improve cognitive function in patients with Alzheimer's disease and stroke. The purpose of this study was to investigate how Cerebrolysin therapy enhances cognitive recovery for mild traumatic brain injury patients using a double-blinded, placebo-controlled, randomized phase II pilot study. Patients having head injury within 24 h sent to our hospital were screened and recruited if patients were alert and conscious, and had intracranial contusion haemorrhage. From July 2009 to June 2010, totally, thirty-two patients were recruited in the double-blinded, placebo-controlled, and randomized study. Patients were randomized to receive Cerebrolysin (Group A, once daily intravenous infusion of 30 mL Cerebrolysin over a 60-min period for 5 days) or placebo (Group B, same dosage and administration of normal saline as Group A). The primary outcome measures were differences of cognitive function including Mini-Mental Status Examination (MMSE), and Cognitive Abilities Screening Instrument (CASI) scores between baseline and week 1, between baseline and week 4, and between baseline and week 12. Thirty-two patients completed the trial. For Group A, the CASI score difference between baseline and week 12 was 21.0 ± 20.4, a significantly greater change than that of Group B (7.6 ± 12.1) (p = 0.0461). Besides, drawing function (one of the domains of CASI; p = 0.0066) on week 4 and both drawing function (p = 0.0472) and long-term memory (one of the domains of CASI; p = 0.0256) on week 12 were also found to be significantly improved in the patients receiving Cerebrolysin treatment. Our results suggest that Cerebrolysin improves the cognitive function of the MTBI in patients at 3rd month after injury, especially for long-term memory and drawing function.