Not only does paratuberculosis cause dramatic economical loss in sheep farming but furthermore attracts attention because of the possible relationship with Crohn's disease in human subjects. There is scant information on the ovine disease and the validity of diagnostic methods is better known in bovine paratuberculosis. In addition, some strains of MAP are very difficult to culture, so the golden test can't be used easily in sheep. This study was aimed at screening paratuberculosis in the sheep population of Viterbo province and at obtaining further information on diagnostic methods. The investigation was at an slaughter on 300 adult sheep from 100 breeding centres. Diagnostics were carried out by PCR using IS900 as primer. Several specimens (faeces, mesenterial limph nodes, mammary limph node, ileocecal valve) from each animal were tested. Out of these 300 sheep, 83 blood samples were also tested with ELISA.Forty-five animals were negative in both tests, 27 animals were positive in tissue specimens and among 10 were positive in faeces with PCR. With ELISA, 21 animals were positive and 10 were doubious.Comparing PCR and ELISA, 18 sheep resulted being positive in both tests, while 3 animals were only positive in ELISA and 9 were positive in PCR only in tissues. The authors suggest that differing positive results may reflect different stages of the disease. The ELISA S/P value has been also under study and debated.