Statement of purpose Traditional all-terrain vehicles (ATVs) are designed for one rider only. The study objective was to better understand the effect passengers have on the mechanisms and injuries seen in ATV crashes.

Methods/approach A retrospective chart review and analysis was performed of trauma registry patients with ATV-related injuries at the University of Iowa from 2002–2013.

Results 537 cases were included in the analysis of which 20% were passengers or drivers with passengers. Both children and females were more likely to be passengers (p < 0.0001). Although helmet use was low (20%), drivers were more likely to wear helmets than passengers (p = 0.02). Rollovers (52%) were the most common mechanism of injury. Rollovers on sloped terrain were more likely to have passengers (p = 0.03). Backward rollovers were almost twice as likely to have passengers as all other rollovers. Victims that had falls/ejections to the rear were nearly eight times more likely to have been on an ATV with passengers than other types of ejections. They were also more likely to have passengers than those involved in non-ejection events (p < 0.0001). Victims who fell or were ejected to the rear had worse head injury scores than those with side or self-ejections (p = 0.001). Self-ejections and forward ejections were less likely if passengers were present (p = 0.0001), and had the highest extremity injury scores (p < 0.0001).

Conclusions Passengers on ATVs may be at greater risk for fall/ejection to the rear which appears to increase the risk of head injury. ATV operators who self-eject receive extremity injuries but may be more able to protect their heads; passengers limit the ability of a driver to self-eject when losing vehicle control.

Significance and contributions This study provides insight on how passengers on ATVs may contribute to crash likelihood and injury severity. A strict no rider rule could reduce risk of some ATV crashes.