Sheep and lamb losses to predators have been determined since 1958. Predators kill many more lambs than sheep and therefore the upward trend of lamb losses in relation to sheep losses indicates that relative predator losses are increasing. Losses were estimated separately for each of the 33 states that showed definite losses and were then added together for areas and for the United States. The fact that independent estimates of predator losses in National Forest regions showed a high correlation with losses estimated from U.S. Department of Agriculture mortality data helps verify the accuracy of each set of estimates. During the 21-year period from 1958 through 1978, the area of predator damage was enlarged as losses tended to increase both eastward and southward. In general, adult sheep losses were about one third as great as lamb losses in the range states and two thirds as great in the farm states. Total numerical losses of sheep and lambs to predators were 1.5 million head in 1958 and 1.3 million in 1979. The percentage of loss steadily increased from 4.0 in 1958 to 6.8 in 1977, the year of the greatest percentage of loss. Sheep numbers declined during this period, in part because of predator losses. In fact, predator losses appear to have been a major cause of the decline of the sheep industry since 1960. The value of the loss increased fairly steadily from a low of $25 million in 1961 to a high of $103 million in 1979, the most recent year statistics were available. All of the eastern states showed relatively minor losses when compared with losses in the western states. Predator losses have had a significant effect on income from sheep. On the average, net income per ewe in 1974 would have increased from $3.88 to $8.12 if predator losses could have been eliminated.