The studies pertained determination of lymphocyte T and B levels and levels of their subpopulations (Th, Tc/Ts, CD25+ cells) in peripheral blood of rabbits infected with two Czech strains, CAMPV-562 and CAMPV-558 of RHD virus, in hours 0, 4, 8, 12, 24, 36 following the infection. The studied lymphocytes were identified using flow cytometry and monoclonal antibodies reactive with CD5+ (for lymphocytes T), CD4+ (for lymphocytes Th), CD8+ (for lymphocytes Tc/Ts), CD25+ and with IgM receptor on lymphocytes B. In individual hours disease signs and mortality of rabbits were also recorded. Analysis of the results proved that the two Czech strains of RHD virus induced a similar immune response in the range of the studied lymphocytes although the response was more intense in rabbits infected with CAMPV-562 and it involved CD25+ cells and lymphocytes B. Clinical signs induced by the two strains were similar but the mortality was different: it amounted to 65% in rabbits infected with the CAMPV-562 strain and just 5% in rabbits infected with the CAMPV-558 strain.