Two experiments were conducted to determine the effects of snowmobile traffic on forage stands in Quebec. In exp. I, two trial areas received 150 snowmobile passes a week for two winters from the beginning of December to the end of March. Three timothy legume swards (alfalfa, red clover, ladino clover) treated with snowmobile traffic showed no significant effects on yield or botanical composition. In exp. II, established forage stands in farmers’ fields crossed by snowmobile club trails were used over three consecutive winter periods. Spring soil-root core samplings taken on 30 location years showed a reduction in yield and legume stands following snowmobile traffic. No significant difference was found in the proportion of grasses but weed numbers increased. The factors believed to influence the yields and botanical composition were also investigated by using step-wise regression analysis. Yields and proportion of legumes and weeds were affected most by winter rain, snow depth and the clay content of the soils, respectively. The results suggested that snowmobile traffic in farmers’ fields was detrimental to alfalfa. Snowmobile trails should avoid legume fields and be located on waste lands, even though this may cause a lengthening of the trails.Key words: Snowmobile, cold hardiness, snow compaction, forage crops