A study was made of 16 bedridden elderly stroke patients. A 10-min skin rubdown for about 10 min was administered for 10 days. Blood was collected at noon on the day before skin rubdown, 5 days and 10 days after initiation and 5 days after completion, and the neutrophil count, lymphocyte count, serum gamma globulin and C-reactive protein (CRP) levels and natural killer cell activity were measured. In nine of these 16 patients, B, T, CD4 and CD8 lymphocyte counts were also measured on the same days. There were no significant changes in the time course of the lymphocyte count, gamma globulin or CRP levels. The neutrophil count increased 10 days after initiation of the skin rubdown, and natural killer cell activity increased 5 days and 10 days days after initiation, and returned to the baseline level 5 days after completion. Although there were no changes in the time course of the B, T, CD4 and CD8 lymphocyte counts, the CD4/CD8 ratio showed an increase 5 days after initiation and completion. The authors concluded that skin rubdown activates natural killer cells, which may be attributed to the effect of certain mediators released from the T lymphocytes and/or the stimulated effect on the sympathetic nerves.