The presence of Paratuberculosis in roe-deer and in small ruminants -grazed on the same pastures- was investigated in NW Apennines (Alessandria province). Serum samples (N=94) and mesenteric lymph nodes (N=47) were collected from 94 roe deer culled in game reserves (GRs) within the study area. No paratuberculosis clinical and post-mortem signs were observed. Sera from 109 small ruminants (56 goats, 53 sheep), bred on 7 farms located within the above GRs, were also collected. Antibodies against Mycobacterium paratuberculosis (M.p) were detected (ELISA test) in 13 roe-deer (13.8%), 7 goats and 1 sheep (7.3%) sera. Sero-positive small ruminants were from 3 flocks: in particular, 4 of 6 positive goats (from a 19 head flock, with high seroprevalence) showed specific clinical symptoms. Difference in sero-prevalence amongst small ruminants flocks -characterised by presence or absence of clinical signs, but with sero-reactors- was statistically significant (P= 0.004, Fisher's exact text), while the difference in sero-prevalence between domestic and wild ungulates was not significant. As regards lymph nodes analysis, acid-fast organisms (Ziehl-Neelsen staining: Z.N.) were detected in 23 samples (49%), and M. p. DNA (Nested PCR, IS900) was found in 17 samples (36.2%). Agreement between results of Z.N. and Nested PCR was evaluated by Kappa coefficient (K=0,40). Moreover, ongoing bacteriological tests allowed to isolate M.p. in 5 out of the 15 roe deer samples so far tested, and in one sick sero-positive goat slaughtered on purpose. Although clinical and gross pathological signs of paratuberculosis in roe deer have not yet been observed, the results of this research suggest that M.p. is widely present within the studied roe deer population. Small ruminant sero-reactors seem to be clustered at flock/farm level, while sero-positive roe deer are present throughout the whole area. Epidemiological patterns of paratuberculosis infection in sympatric roe deer and small ruminant populations are still being investigated.