To determine the clinical outcome and mean length of hospital stay of paediatric patients with severe blunt traumatic head injury (THI) receiving 3% hypertonic saline (HTS) in the Emergency Department (ED). This case series study was conducted at the Department of Emergency Medicine, Aga Khan University Hospital, Karachi, from 2014 to 2015 via chart review of 105 patients. Detailed history and clinical examination of all paediatric patients aged 2-16 years was recorded which included moderate to severe head injury as classified by the Glasgow Coma Scale (GCS) by the Brain Trauma Foundation. As per routine care after admission of such a patient, for resuscitation 3% HTS was administered. GCS was recorded at 6 hours and at the time of discharge. Of the 105 patients, 76 (72.4%) were male and 29 (27.6%) were female, and the mean age was 61.6+45.9 months. Traumatic brain injury (TBI) was found moderate in 60 (57.1%) cases and severe in 45 (42.9%) of our patients as per the GCS. Six hours after resuscitation with 3% hypertonic saline, 45 (43%) patients normalised as per GCS, 39 (37%) patients had moderate TBI and 21 (20%) had severe TBI. Forty five patients had a hospital stay of 2-3 days. The GCS improved after resuscitation with 3% hypertonic saline in emergency department, with a mean length of stay of 4.6+3.9 and 12.6+10.7 days in moderate and severe head injury respectively with a P value of <0.001, and was normal in 94 (89.5%) patients at the time of discharge. Paediatric patients with TBI receiving 3% hypertonic saline results in improved GCS and a decrease in the length of hospital stay.