Australian Design Rule (ADR) 22A requires head restraints to be fitted to driver and front left seats of all new cars in Australia from 1975 model onwards. It upgraded ADR 22 by requiring the head restraints be not adjustable below a specified minimum height. This study was based on 1977-78 claims to a "no-fault" injury compensation scheme operated by the Motor Accidents Board (MAB) in Victoria. Potential benefit groups (front outboard seat occupants in rear end impacts) and disbenefit groups (front and rear seat occupants in front end impacts) were considered. The study concluded that ADR 22A head restraints are effective in reducing whiplash injuries to female front occupants aged 17-49 involved in rear end impacts. The analysis was inconclusive regarding the benefits to male front occupants in these impacts due to the possibility that their benefit (if any) from ADR 22A may be off-set or eroded by an increase in whiplash injuries due to increased seat belt wearing in the front seats of ADR 22A cars, resulting in little or no apparent benefit.