The effects of physical therapy on immunological parameters were evaluated in 22 patients (14 males, aged 68.1 +/- 9.9 years) with cerebrovascular diseases in a stable situation 3 to 6 months after the onset of stroke who were entered into a rehabilitation program in our hospital between 1990 and 1993. The proportion of CD4+ cells was significantly increased but that of CD8+ cells was decreased throughout the rehabilitation program, resulting in an increase in the ratio of CD4+/CD8+ cells. The lymphocyte response to phytohemagglutinin and concanavalin A was increased, while no significant differences were observed in CD3+ cells, natural killer cell activity, and serum levels of immunoglobulins, interleukin-1 beta, interleukin-2 and interleukin-6. These findings suggest that repeated physical exercise may activate the immune system, especially T-cell function, for possible prevention of infectious diseases that are often complicated in patients with cerebrovascular diseases.