Background Clinical experience suggests that anaesthesia using a combination of acupuncture and drugs can reduce the dosage of anaesthetics required for craniotomy, decreasing both the disturbance in physiological functions during the operation and postoperative complications and improving the rate of recovery. The aim of the present study was to investigate the impact of electroacupuncture (EA) on the dynamic equilibrium of the immune system and immune cell populations during the pericraniotomy period. Methods A total of 56 patients undergoing craniotomy were randomised into three groups: control (C, n=18), EA (A, n=19) and sham acupuncture (S, n=19) groups. Blood samples were collected before anaesthesia (TO) and 30 min, 2 h and 4 h after induction of anaesthesia (T1, T2 and T3, respectively,) to measure the levels of tumour necrosis factor alpha (TNF alpha), interleukin (IL)-8, IL-10, IgM, IgA, IgG and full blood count. Results There was no significant difference between the measurements in groups A and S during craniotomy. The levels of IgM and IgA decreased significantly in group C compared with groups A and S at T2 and T3 time points. The levels of total T cells and suppressor T cells in group C decreased significantly compared with groups A and S at T1 and T2, and the level of natural killer cells in group C decreased significantly compared with groups A and S at T1. No significant differences between groups were found in the levels of TNF alpha, IgG, IL-10, IL-8, leucocytes, neutrophils, monocytes, Th cells or B cells. Conclusions EA appears to reduce immunosuppression of both the humoral and cellular components during surgery.