The objective of this study is to describe severe road traffic injuries (RTIs) in the population under 18 years in Belgrade, the capital of Serbia. We analysed both severe non-fatal and fatal RTIs in children and adolescents under 18 years old in the Belgrade area, during the period 2008–2011. Data sources were the official statistics of the Public Health Institute in Belgrade and forensic-medical records from two paediatric university hospitals and five university hospitals for adults. Using descriptive statistical methods, demographic characteristics, mechanism, type and time of injuries, surgical treatment procedures, injury severity scores (ISS), length of stay and outcome were evaluated. The admission and mortality rates were calculated. Among the total of 379 injured, 256 (67.5%) were male; the average age was 13.0 ± 4.7 (range: 0–18 years). The annual hospital admission rate of RTIs for both sexes decreased in average by 12.6% (95% CI = 9.3%–15.9%). The mean percentage of annual changes of mortality rates was 2.0 %; 95% CI = 1.3%–5.3% (5.7 per 100,000 in 2008, 5.6 in 2009, 4.7 in 2010 and 5.9 in 2011). The highest admission rates and mortality rates were for pedestrians, followed by passengers and cyclists. Accidents occurred most commonly on Monday (18.7%). Among children hospitalised for traffic injuries, 57.8% had head and neck trauma, 30.6% extremity fractures, 5% abdominal injuries, 4.2% chest and 2.4% multiple injuries. The average ISS was 22.4 (SD = 20.4), ranging from 1 to 75. Alcohol in blood was confirmed in 7.4% males and 3.3% females (p > 0.05). The average time of hospital stay was 8.8 days (SD = 16.7), ranging from 1 to 14. The increased rates require implementation of a well-defined national strategy in our country.