A windbreak was erected in a wheat field during the growing seasons of 1960 to 1964 inclusive. The effect of this barrier on wind travel, evaporation, and wheat yield was measured. The use of snow fencing, erected each year after seeding, eliminated the effect of snow accumulation on the grain yield of sheltered fields.The windbreak reduced wind travel by 15 to 49% during the five-year test period and led to reductions of 12 to 23% in evaporation from Bellani plates. Yields within the sheltered area ranged from 24 to 43% above check yields. Maximum grain production was obtained in the area of maximum wind and evaporation reduction. However, yields in general were extremely variable throughout the test area during individual years, and from year to year. The wide variations in yield suggest that the effects of windbreaks on other environmental factors should be considered in studies of this nature.