Abstract： Objective To investigate whether pituitrin can lower 28-day mortality as compared with treatment with norepinephrine (NE) in patients with septic shock.Methods Randomized,controlled,open-label trial was conducted.One hundred and thirty-nine septic shock patients with dopamine requirements exceeding 5 μg· kg-1· min-1 were divided at random into two groups as the study group and control group.All patients enrolled were treated by the same treatment principle and measures.In patients of study group injection of pituitrin 0.017-0.042 U/min ( 1.0-2.5 U/h) was given,and if hemodynamics was still unstable,catecholamines was added to obtain the target blood pressure; while in the control group catecholamines was given to maintain stability of hemodynamics.Results Among 139 patients enrolled in the study,66 composed of the clinical study group and 73 in the control group.The main principle of the treatment in the two groups was similar.There was no significant difference in overall 28-day mortality rate between study group and control group (40.9％ vs.46.6％,P＞0.05).In patients whose acute physiology and chronic health evaluation Ⅱ ( APACHE Ⅱ ) score was less than 25,the mortality of study group was significantly lower than that of control group [ 10.3％ ( 3/29 ) vs.35.7％ ( 10/28 ),P＜0.05 ].The length of stay in intensive care unit [ ICU,days: 5(3,8) vs.5(3,8)],and duration of mechanical ventilation [days: 4.0 (2.8,6.0) vs.4.0 (2.0,5.0)] were similar in two groups (both P＞0.05).The dosage of NE (μg/min: 7.99 ±5.02 vs.10.12 ±5.12) and heart rate (beat/min: 93.27 ± 7.84 vs.108.45 + 12.31 ) were significantly lower in study group compared with that of control group (both P＜0.05 ).Serum creatinine and lactate levels in the two groups were similar at baseline,and creatinine [ μmol/L:87.5 (62.8,157.0 ) vs.76.0 (52.5,117.0) ] and lactate level (mmol/L: 3.72 ± 2.47 vs.3.53 ± 1.86) were still similar in two groups 24 hours later (all P＞0.05 ).The rate of use of glucocorticoid (43.9％ vs.31.5％ ) and heparin in small dosage (42.4％ vs.41.1％) had no significant difference between two groups (bothP＞0.05).Conclusions Combined use of pituitrin in patients with septic shock can reduce the dosage of catecholamines,and decrease the heart rate.Although it can not lower the overall mortality of septic shock,among patients with less severity whose APACHE Ⅱ score lower than 25,low-dose pituitrin in conjunction with catecholamine vasopressors can reduce 28-day mortality.