Paratuberculosis was diagnosed in 1988 in South Africa on histopathological examination of an emaciated sheep which originated from a flock of sheep at an agricultural research station in South Africa. This paper deals with the findings from 135 slaughtered sheep from the above paratuberculous flock. The sheep had not been selected as suspected clinical cases of paratuberculosis. The sheep were examined via the agar gel immuno-diffusion (AGID) test and complement fixation test (CFT), microscopic examination of fecal and intestinal smears, culture and histopathological examination, predominantly of the ileum. The AGID test was strongly positive in 3.1% and weakly positive in 13.9% of the sera. The CFT was positive in 2.3% of the sera. The infection rate by microscopic examination of smears was 2% for feces, 11.1% for the ileum and 10.3% for the caecum. M. paratuberculosis has so far been cultured from 4 cases. Histopathological evidence of paratuberculosis was found in 11% of cases examined. There seems to be a poor correlation between the results obtained by the above methods. This demonstrates the necessity of using several available methods in order to attain quantifiable results with reasonable accuracy.