Animals sometimes injure trees by eating the leaves. Little is known about the amount of removal required to harm survival and growth, particularly of southern pines. To simulate a single defoliation by livestock or wildlife, needles of slash pine were hand clipped once at 6, 18, and 30 months after planting. Survival and height growth were measured for six growing seasons after removing 0, 25, 50, 75, and 100% of the foliage. Survival was excellent except when 100% of the needles were removed 6 months after planting. Reductions in rate of height growth occurred only with the most severe levels of defoliation and were still apparent for 3 years after treatment. Even so, the greatest accumulated loss in height was less than 1 m over the 6-year period. Cattle and other animals sometime eat the foliage of trees, even resinous pine needles. However, Cassady et al. (1955) and Pearson (1976) observed that cattle rarely graze pine The author is principal range scientist, Southeastern Forest Experiment Station, Forest Service, U.S. Department of Agriculture, Marianna, Florida 32446. This was a cooperative study by the Georgia Coastal Plain Experiment Station, University of Georgia, College of Agriculture, Tifton, Ga., and the Forest Service, USDA. Acknowledgement is given to Dr. Karl F. Wenger, whose idea prompted the study, and to Ralph H. Hughes, who initiated the study. Manuscript received March 12, 1979. foliage when other green forage is available. The quantity of needles eaten varies with rate of cattle stocking, abundance and variety of other forage, season of grazing, seedling condition at time of planting, and seedling size. Various attempts to assess needle removal under actual grazing conditions have been too imprecise to evaluate or to predict subsequent tree performance. However, an understanding of defoliation impacts is necessary in devising plants for integrated management of forested ranges. This study evaluates the impact of simulated defoliation by cattle on survival and height growth of slash pine (Pinus eZZiottii Engelm.). Five degrees of seedling defoliation were simulated by hand clipping at three plantation ages.