Background There are major gaps in contemporary knowledge regarding the burden and risk factors for road traffic injuries (RTI) in Pacific Island countries. Aim To investigate the epidemiology of RTI and the contribution of driver sleepiness to fourwheel motor vehicle crash injuries in Viti Levu, Fiji. Methods Systematic reviews evaluated the published evidence on: (1) the burden of RTI in Pacific Island countries; and (2) the role of driver sleepiness in motor vehicle crashes in low- and middle-income countries (LMIC). Subsequently, three population-based studies were conducted in Viti Levu: (1) an analysis of the Fiji Injury Surveillance in Hospitals database to describe the incidence and characteristics associated with RTI; (2) a cross sectional roadside survey of 752 drivers to estimate the prevalence of driver sleepiness; and (3) a case control study (131 cases and 752 controls) to investigate the contribution of driver sleepiness to the risk of four-wheel motor vehicle crashes involving fatal or hospitalised injuries. Results Systematic reviews: Based on 19 studies identified, all of which were published more than 15 years ago, data on the burden of RTI in Pacific Island countries and territories is largely descriptive with limited evidence on aetiology. Ten studies from LMIC, largely focused on heavy vehicle drivers, suggest that daytime sleepiness increases the risk of road crashes. Study 1: During the 12-month study period, fatal and hospitalised RTI in Viti Levu most commonly involved males (72%) and people aged 15 to 29 years (33%). Two thirds of deaths occurred before hospitalisation and fatality rates were higher among Indians compared to Fijians. Studies 2 and 3: 18% of driving time was undertaken by drivers who reported being sleepy (1%) or not fully alert (17%). After adjusting for confounders, driving while sleepy or not fully alert was associated with an almost six-fold increase in the odds of injury-involved crashes (OR 5.7, 95% CI 2.7, 12.3). The corresponding population attributable risk was 34% (95% CI 28.6, 39.5). Conclusions Addressing RTI in Pacific Island countries and territories should be a public health priority with particular attention to the role of driver sleepiness, a poorly characterised risk factor for four-wheel motor vehicle crashes in less-resourced settings.