In sheep Psoroptes ovis provokes an allergic dermatitis with significant P. ovis antigen-specific IgE responses. The kinetics of the IgE response to primary and challenge infestations of P. ovis were reported earlier [Parasite Immunol. 22 (2000) 407]. The present study examines IgG, IgM and IgA responses to primary and challenge infestations of P. ovis and the profile of antigens/allergens reacting with IgG and IgE antibodies. Antigen-specific enzyme-linked immunosorbent assays (ELISAs) demonstrate that primary infestations elicited significant increases in levels of IgG and IgM but not IgA antibodies. IgG and IgM responses to primary and challenge infestations were not significantly different. Western blots of reduced P. ovis proteins indicate that IgG antibodies reacted with five major antigens following primary infestation and only three of these after challenge infestation. IgE antibodies bound to three major and five minor allergens after primary infestation and two additional minor allergens after challenge infestation. Immunodominant antigens >100 and <15 kDa and allergens >100 kDa were most consistent in stimulating substantial IgG and IgE antibody responses, respectively. These antigens/allergens may be exploited in immunodiagnosis and modulation of the host immune response.