Tractor roll-overs are the leading cause of fatal farm accidents, accounting for more than one-fourth of all agriculturally related deaths. Most of these deaths could be prevented if the tractors were equipped with roll-over protective structures (ROPS). This study estimates the number of tractors in New York without ROPS, projects their retirement, and then estimates the number of lives which would be saved if ROPS were retrofitted on old tractors. The basic costs associated with mandating ROPS are calculated from these estimates. The minimum economic cost of mandating ROPS is $511,136 per life saved for the retrofits, and an additional $253,254 per life saved for every $1 million spent annually on enforcement. It is concluded that a policy mandating ROPS on all tractors would be expensive, but should be considered with particular attention to the need for and cost effectiveness of enforcement.