The purpose of this study was to investigate the effect of swimming exercise and DHEA administration on the levels of T-cells(CD3), B-cells(CD19), helper-T cells(CD4), suppressor-T cells(CD8) and NK-cells(CD16+CD56) in elderly women. 27 elderly women were selected as participants. There were three groups which include the exercise+DHEA group, the exercise group, and the control group, respectively. The participants completed the swimming exercise program with an exercise intensity of 50-60% HRmax for 55 minutes a day, three times a week for 8 weeks. The results of the study are as follows. No significant changes in the levels of T-cells, B-cells, helper-T cells, suppressor-T cells, and NK-cells were found in the exercise group and the control group. However, significant changes in the levels of helper-T cells and NK-cells were found in the exercise+DHEA group. This result showed that the co-treatment of exercise+DHEA somehow affected immune system in the elderly women. This is likely to be attributable to the fact that the increased IL-2 level caused by the co-treatment of swimming exercise and DHEA administration promoted helper-T cell proliferation, increased activities of NK-cells and cytptoxic T-cells, and antibody formation. However, no significant changes were found in most immune cells, which indicated that the 8-week period of study was insufficient to investigate the effect of exercise+DHEA administration on the immune system. Therefore, a further study on the effect of exercise on immune system is required to perform the elderly population with immune system level below the normal level.