During 1983 and 1984, ileocecal lymph node specimens were obtained from clinically normal cattle at 76 USA Department of Agriculture-inspected cull cattle slaughterhouses in 32 states and Puerto Rico. M. paratuberculosis was isolated from the lymph nodes of 119 of 7,540 cattle. The prevalence of bovine paratuberculosis was 1.6% overall, with 2.9% in diary culls and 0.8% in beef culls. The prevalence for females and males did not appear to differ significantly.