The National Animal Health Monitoring System (NAHMS) is sponsored by the USDA:APHIS:Veterinary Services (VS). The NAHMS Equine '98 Study was designed to provide information about the nation's equine population for education and research purposes. This report is based on the second phase of Equine '98 data collection done by Federal and State Veterinary Medical Officers (VMO's) and Animal Health Technicians (AHT's) in 28 states. From June 15 through September 11, 1998, horse management and health data were collected on-farm from 1,136 participating operations that had three or more horses present on January 1, 1998. This target population was estimated to represent 51.6 percent of operations with horses in the 28 states and 83.9 percent of horses in the 28 states. Race tracks were not included in this phase of the study. The majority (94.0 percent) of operations provided resident horses access to pasture in 1998. Overall, greater than 50 percent of operations with pasture access for horses had surface water, such as a stream, lake, pond, or irrigation ditch in the pasture itself. Approximately one-third of operations had resident stallions. Of the operations with stallions, just under one-half (47.6 percent) used one or more of these stallions for breeding purposes in the previous 12 months. Of the operations that used stallions or breeding in the previous 12 months, only 3.0 percent shipped semen within the U.S. and 0.1 percent shipped semen internationally. Over 88 percent of operations had resident mares in the previous 12 months, although not all operations used these mares for breeding purposes. For operations with mares, 42.3 percent used one or more of these mares for breeding purposes in the previous 12 months. Overall, 59.4 percent of operations had never heard of equine viral arteritis (EVA). Approximately two-thirds of operations had never heard of vesicular stomatitis (VSV). Contact for this paper: Lindsey Garber.