In a previous paper we reported that electroacupuncture (EA) could suppress opioid withdrawal syndrome and increase the appetite, sleep, and body weight in heroin addicts or morphine dependent animals. Considering that opioids were known to inhibit immune function, the present study was designed to observe whether EA could modulate the immune status of morphine dependent and withdrawal mice. We found that chronic morphine-induced decrease of splenic T lymphocyte proliferation and IL-2 production can be significantly raised by 2 Hz EA, and the fluctuation of CD4+/CD8+ ratio was also run to the baseline level by the EA. These findings indicated that chronic morphine exposure-induced immune dysfunction in mice could be normalized by 2 Hz EA.