Paratuberculosis was diagnosed in a herd of 62 fallow deer (Dama dama) and 38 sika deer (Cervus nipon) maintained in an animal park in Ohio. A comparison was made of delayed-type hypersensitivity responses, results of in vitro lymphocyte immunostimulation tests, and isolation of Mycobacterium paratuberculosis on fecal culture in 19 deer.