Highlight: Big sagebrush (Artemisia tridentata) fed to sheep by stomach pump to study its abortifacient properties during the 2nd trimester of pregnancy produced no reproductive difficulties. However, big sagebrush was lethal when % lb was fed by this method daily for 1, 2, or 3 days. Sagebrush fed 54’ lb daily and slowly increased to % lb daily was not toxic. These findings confirm many general reports of suspected sagebrush toxicity and indicate the need for caution in moving sheep rapidly onto big sagebrush areas. Juniper (Juniperus osteosperma) fed to sheep in 1 lb daily amounts in an interrupted series of feedings totaling 30 days in the 2nd and early 3rd trimester of pregnancy caused abortion in 2 sheep and birth of a weak lamb from a 3rd sheep. Attempts to confirm these findings by feeding juniper to other sheep during gestation days 60 to 90 were unsuccessful. sagebrush (A. tridentata), which includes several sub and cross species, may be found on a variety of soil types at elevations of 2,00010,000 feet and is heavily utilized as food by both domestic and wild ruminants. At many lower elevations sheep may graze for 5-7 months of the year on winter ranges composed almost entirely of big sagebrush (Cook et al., 1954). Another sagebrush, black sagebrush (A. nova), considered in many areas to be a climax plant, is highly palatable to sheep and has long been classed a valuable browse plant (Hutchings, 1954). It, thus, is sought and utilized highly by sheep. Additionally, wild ruminants, especially deer, are forced in many areas of the West to rely more and more on sagebrush and juniper as major winter maintenance plants. Sagebrush species have long been suspected of being toxic