The influence of intensive Judo training on serum immunoglobulins IgG, IgM, and IgA was studied in 24 Judo fighters. Subjects were assigned to an exercise training group (EXE; n=12) and non-exercise control group (Con; n=12). Subjects in EXE group participated in exercise sessions 4 days a week for 8 wk. Serum samples were collected before, immediately and 1wk after study period. The IgG levels were significantly increased immediately after exercise training (p=0.001) in EXE compared to Con. However, IgM and IgA concentrations showed significant decrease immediately after exercise in EXE (p=0.001). The concentrations of all immunoglobulins had returned to baseline by 1wk of recovery. In conclusion the increased IgG levels are possibly due to isotype switching or a secondary antibody responses that could be considered as enhancement in immune system function. However, chronic suppression of immuniglobulins IgM and IgA may be mediated by hormonal changes associated with exhausting exercise.