The purpose of this study was to systematically search the literature and analyze evidence from randomized controlled trials (RCTs) comparing tolvaptan with conventional diuretics for postoperative fluid management in cardiac surgery patients. An electronic search of PubMed, Scopus, BioMed Central, CENTRAL (Cochrane Central Register of Controlled Trials) and Google scholar databases was carried out up to 1st December 2019. Four RCTs were included. Tolvaptan was co-administered with conventional diuretics in all the studies. The mean postoperative urine output was significantly greater in patients receiving tolvaptan as compared to controls (MD=0.39; 95% CI: 0.17 to 0.61; P=0.006, I2=48%). Body weight of patients on tolvaptan returned to pre-operative levels significantly earlier (MD=-1.57; 95% CI: -2.48 to -0.66; P=0.007, I2=50%). There was statistical significant difference in the highest postoperative serum sodium levels (MD=2.34; 95% CI: -1.65 to 3.03; p<0.00001, I2=0%), lowest serum sodium levels (MD=2.05; 95% CI: 1.41 to 2.68; p<0.00001, I2=0%) and mean serum sodium levels (MD=1.69; 95% CI: 0.98 to 2.40; p<0.00001, I2=0%) between the tolvaptan and control groups. Lowest serum potassium was significantly higher with tolvaptan as compared to the control group (MD=0.10; 95% CI: 0.01 to 0.18; P=0.03, I2=19%). There was no significant difference in the length of ICU stay or incidence of arrhythmias between the two groups. The quality of the included studies was not high. Within the limitations of our study, our results indicate that co-administration of tolvaptan with low dose of conventional diuretics significantly increases urine output while maintaining electrolyte balance in postoperative cardiac surgery patients. Faster return of body weight to pre-operative levels is evident with tolvaptan. Further high-quality RCTs are required to confirm this evidence. Copyright: © Chen et al.