The aim of this study was to relate discharge King's Outcome Scale for Childhood Head Injury (KOSCHI) category to injury severity and detailed outcome measures obtained in the first year post-traumatic brain injury (TBI). We used a prospective cohort study. Eighty-one children with TBI were studied: 29 had severe, 15 moderate, and 37 mild TBI. The male:female ratio was 1.8:1. The mean age was 11 years 10 months (SD 3.6, range 5–16y). Discharge KOSCHI categories were good (n=34), moderate (n=39), severe (n=6), and unclassifiable (n=2). KOSCHI category correlated strongly with admission Glasgow Coma Score, length of hospital stay, and post-traumatic amnesia. It also correlated significantly with Verbal IQ and Performance IQ (Wechsler); measures of attention; health status (Health Utilities Index [HUI]); health-related quality of life (Pediatric Quality of Life Inventory [PedsQL]); depressive symptoms (Birleson Depression Scale) assessed within 3 months post-TBI; and with Verbal IQ, selective attention (map mission), and HUI and PedsQL domains assessed at least 6 months post-TBI discharge. KOSCHI did not correlate with behaviour or executive function. We conclude that the KOSCHI scored at hospital discharge correlates with severity of injury and some cognitive, health status, and HRQL outcomes early after TBI. It is not helpful at predicting later difficulties, or behavioural and emotional problems.