Ovine Johne's Disease was first diagnosed in NSW in 1980. An intensive surveillance program was carried out from April to July 1998 to better define the distribution and prevalence of the disease. More than 800 investigations were made on over 650 flocks from throughout NSW. The gel test was performed on more than 100,000 blood samples with reactors necropsied and intestinal sections submitted for histopathological examination. Blood samples were derived from two main flock categories - those identified as "at risk" because they had purchased sheep from or had other contact with known infected properties or those with no known risk factors that wished to demonstrate their freedom from the disease (eg Market Assurance Program testing). Analysis of the results of serological and histopathological testing will be reported. They provide a useful guide to the testing strategies most suited to a surveillance program of this type.