The protozoan diseases, coccidiosis and cryptosporidiosis, are important enteric diseases of sheep and goats, resulting in diarrhea, inefficient weight gains, and occasionally death. Coccidiosis is a widespread, serious economic disease affecting animals who are preweaned, recently weaned, or in unsanitary, stressful, or crowded conditions, as well as after entering feedlots. The Eimeria species in sheep and goats are relatively host specific. Control is accomplished through sanitation and by incorporating one of the modern coccidiostats, such as lasalocid or decoquinate, in feed or salt to ensure an intake of approximately 1 mg of drug per kg of body weight per day for at least 30 consecutive days. Prevention and control of coccidiosis results in significantly greater weight gains and production, whereas disease with or without treatment is likely to result in inefficient production and economic loss to the producer. Cryptosporidiosis, caused by Cryptosporidium parvum, is primarily a disease of lambs and kids less than 30 days of age and is usually a milder disease than coccidiosis. Infective oocysts are passed in feces and are transmitted by oral ingestion. Oocysts readily infect a variety of animals, including humans. Cryptosporidiosis is a prevalent disease in neonatal ruminants and in humans. Effective treatments are not available, but because the disease is usually mild and self-limited, supportive care, primarily hydration, is important. Control is strict sanitation and quarantine of sick animals. Disinfection of contaminated housing with ammonia or formalin will kill the oocysts. The cyst-forming coccidia diseases, toxoplasmosis and sarcocystosis, utilize two hosts in their life cycles: sheep or goats and carnivores. Abortions and reproductive failures are major manifestations of disease. Control is through elimination of carnivore feces from the premises through management.