This study sought to determine whether fitting a more aggressive seat belt reminder system to new vehicles would be cost-beneficial for Australia. While seat belt wearing rates have been observed around 95% in the front seat, non-wearing rates in casualty crashes are as high as 33% among persons killed and 19% among seriously injured occupants. Benefits were computed for three device options (simple, simple-2 and complex) and three introduction scenarios (driver-only, front seat occupants and all occupants). Four levels of effectiveness were assumed, from 10% to 40%, depending on the type of device fitted. Unit benefits were computed assuming a 5% discount rate and a 15yr fleet life. Various industry experts provided the costs. The findings showed that Benefit-Cost-Ratios ranged from 4.0:1 at best (simple device for the driver only) to 0.9:1 for all seating positions. These figures are conservative, given the assumptions made and the discounted human capital methods used.