Abstract： Objective To investigate the effects of prolonged deployment at sea on the neuronendocrine-immune system of submariners.Methods Fifty-five submariners were screened for the study.The levels of creatine kinase (CK),trigeminal ganglion (TG),glucose (GLU) and uric acid (UA) were detected with ELISA,and levels of serum norepinephrine (NE),corticosteroid (COR),heat shock protein (HSP70),interleukin 2 (IL-2) and IL-4 were also detected with testing kits in 36 research subjects.Results (1) The level of NE [(313.68 ±146.51)ng/L] measured after prolonged deployment was significantly higher than that measured before deployment [(224.80 ± 118.52) ng/L] (P ＜ 0.01),the level of COR[(18.40 ± 6.91) μg/L] after prolonged deployment elevated slightly than that before deployment [(14.73 ± 8.70) μg/L] (P =0.075),and the level of HSP70 [(149.02 ± 72.22) μg/L] after the prolonged deployment elevated considerably,as compared with that before deployment [(109.02 ± 59.92) μg/L] (P ＜ 0.05).(2) The level of GLU [(4.27 ± 0.67)mmol/L] measured after prolonged deployment decreased considerably,as compared with that of predeployment [(4.60 ± 0.56)mmol/L] (P ＜ 0.05),the levels of C K,TG and UA [(217.76 ± 181.21)U/L,(2.05 ± 0.91)mmol/L and(407.11 ± 60.81)μmol/L] after the prolonged deployment elevated significantly,as compared with those [(119.67 ± 75.88) U/L,(1.32 ± 0.55) mmol/L and (330.18 ± 70.93) μmol/L] before deployment (P ＜ 0.01).(3) The levels of IL-2 and IL-4 [(424.44 ± 166.04) ng/L,(361.13 ± 163.47)ng/L]measured after deployment were significantly higher than those [(331.95 ±173.11)ng/L and (246.42 ± 166.20) ng/L] before deployment (P ＜ 0.05).Conclusions Prolonged deployment at sea could activate the immune system of submariners to a certain extent and might induce changes in neuroendocrinology.