During a regular annual tuberculinisation on the farm of dairy cows of Frisian breed 12.1% of unspecific reaction to tuberculin was established. Some of the cows had chronic watery diarrhoea and were markedly skinny, thus such clinical symptoms indicated paratuberculosis. The blood samples of 205 cattle on the farm were serologically analysed using the following methods: enzyme - linked immunosorbent assay - ELISA (IDEXX), complement fixation (CF) test and agar gel immunodiffusion - AGID test (Bioveta), Mycobacterium paratuberculosis gamma interferon test kit-gamma-IFN (IDEXX). The allergy test (P.P.D.-Johnin) was also carried out as well as the DNA - test (IDEXX) from the dung of cattle reacting positively or suspiciously with one of the tests mentioned. Applying some of the tests mentioned above, positive reactions were established in 39(19%) out of 205 cattle examined. When using ELISA test positive reactions were established in 20(9.7%) of cattle, with CF test 3 (1.5%) cows were positive and 9 (4.4%) of them suspected, with AGID test 4 (1.95%) of them were positive and with gamma-IFN test reaction were established in 23 (11.3%) cattle. When using the allergy test in 22 (10.7%) cattle the swelling of skin wrinkler greater than 2mm was established and by DNA - probe positive reaction was established in 10 (25.6%) cattle out of 39 samples analysed. Combining several tests (ELISA, gamma-IFN, DNA-probe) and using faecal culture reliable diagnostics of paratuberculosis in cattle can be obtained.