Cytomegalovirus (CMV) and herpes simplex virus type 2 (HSV-2) are widespread among the human population and play an important role in disorders of pregnancy. Anti-CMV antibodies are detected in 40 – 100% of women of childbearing age, and herpes virus prevalence is approximately similar. The authors have studied some biochemical and immunological blood parameters of pregnant women affected by CMV and HSV-2. All patients have been divided into 2 groups: CMV group (22 women) and HSV-2 group (21 women). All parameters were compared with those of a control group (21 healthy pregnant women). The biochemical values included total protein, alanine transaminase (ALT), aspartate transaminase (AST), gammaglutamyltransferase (GGT), and thymol test. The immunological parameters included counts of CD3 , CD4 , CD8 , CD19 , CD56 lymphocytes. The study detected that the biochemical parameters changed more pronouncedly in HSV-2 than in CMV, namely: levels of total and direct bilirubin, ALT, AST, GGT increased significantly. Conversely, decrease of different T-lymphocyte populations was more expressed in CMV than in HSV-2. In both test groups, mostly T-suppressor population count and functional activity decreased. T-lymphocyte count reduction results from direct cytotoxic viral effect on cells, blockade of T-lymphocyte receptors by circulating immune complexes, sialic acids and other metabolites of inflammatory reactions, increase of lymphocyte suppressing factor level in serum, T-lymphocyte redistribution due to their migration to target organs.