The effects of different tractor activities and seat belt use on the protection afforded by roll over protective structures (ROPS) were examined. Information on tractor uses, such as field use, stationary use, and inside use, seat belt use, and other relevant information was obtained by interviewing the operators of 170 farms in New York. Over 56% of the survey respondents were dairy farmers, while 12% were livestock farms. The average farm used four tractors, each of which typically operated 285.1 hours per year. Of the tractors studied, 33.1% had ROPS. While 68.1% of tractors made since 1984 had ROPS, only 4.2% of those made prior to 1964 had ROPS. Tractors equipped with ROPS were utilized more often than other tractors. Field work contributed to 85.6% of tractor operation time, whereas 5 and 8% of the time were spent on stationary tasks and inside work, respectively. About 42.7% of all operation time was spent in tractors with ROPS. If the risk of roll over during stationary and inside tasks was regarded as negligible, the percentage of operation time that farmers were at risk increased by 20% to 51.3% of the time. Of the tractors studied, 26.4% had seat belts, which farmers claimed to use about 31.8% of the time. Thus, the effective use rate of seat belts was only 8%. Tractors equipped with ROPS were significantly more likely to have seat belts than tractors which lacked ROPS. With seat belt use considered in the calculation, the effective protection of ROPS during field activities was between 8.2% and 33.9%, depending on whether cabs were kept closed. The authors conclude that the use of ROPS varies according to tractor activity.