In our previous study we found that electrolytic lesion of the bed nucleus of the stria terminalis (BST) as well as the medial septal nucleus (MS) caused depression of the peripheral blood natural killer cell cytotoxicity (NKCC) in rats. In the present study we evaluated blood NKCC after 14 day electrical stimulation of the BST and the MS in conscious, freely behaving rats differing in responsiveness to novelty. Male Wistar rats divided into high (HR) and low (LR) responders to novelty, implanted with stimulating electrodes at the BST or at the MS, were subjected to 14 day electrical stimulation (constant current 0.1 ms duration cathodal pulses delivered at a frequency of 50 Hz during 30 min) of the BST and the MS. The chronic stimulation of the BST and the MS caused augmentation of blood NKCC in comparison to the sham operated group and to the baseline, which was more significant in HRs. A week after termination of the stimulation procedure NKCC returned to the baseline. The obtained results suggest that immunoenhancing effect on blood NK cell function is dependent on the behavioral outcome (intensive locomotor reaction) of the BST and the MS stimulation as well as on individual behavioral characteristics. This work was supported by a research grant NN303819040.