Abstract Funding Acknowledgements Type of funding sources: None. Introduction Acute heart failure can affect the kidney, which is known as cardiorenal syndrome (CRS) type 1 that may worsen renal function and increase mortality. Ultrafiltration (UF) and loop diuretics are CRS type 1 treatment modalities mainly in improving congestion. Renin-angiotensin-aldosterone system (RAAS) is one of the key role mechanisms in type-1 CRS patients. Previous studies showed inconclusive neurohormonal and kidney parameters outcome comparisons between UF and loop diuretics in type-1 CRS patients. Purpose This study has the purpose to compare the effect of UF and loop diuretics to neurohormonal and renal parameters in type-1 CRS patients. Methods We did comprehensive searching using predefined keywords in online databases of Pubmed, ScienceDirect, EMBASE, and The Cochrane Library to screen all relevant literature until November 2020. We included all randomized controlled trials (RCTs) that compared the neurohormonal and renal parameters between UF and loop diuretics in type-1 CRS patients, not on chronic dialysis therapy and have serum creatinine (SCr) below 3 mg/dL. The neurohormonal parameters analysed in this study are changes of N-terminal pro-brain natriuretic peptide (NT-proBNP), plasma renin activity (PRA), and serum aldosterone, while the renal parameters analysed are changes of SCr, Cystatin-C, and dialysis dependency. We used Cochrane Risk-of-bias tools for accessing bias risk. We performed analysis to provide standard mean difference (SMD) for laboratory parameters and risk ratio (RR) for dialysis dependency with 95% confidence interval (CI) using fixed-effect heterogeneity test. Results We included 11 RCTs met our inclusion criteria. The UF groups showed more NT-proBNP decline compared with the diuretics groups although not statistically significant (SMD = -0.02, 95% CI -0.22 to 0.17, p = 0.80, I²=0%). The UF group showed RAAS activity increment, which are significantly difference in PRA (SMD = 0.38, 95% CI 0.12 to 0.63, p = 0.004, I²=54%) but no significance in aldosterone change (SMD = 0.09, 95% CI -0.17 to 0.34, p = 0.50, I²=0%). Surprisingly, the UF group tends to have incremental dialysis dependency risk although not statistically significant (pooled RR = 1.28, 95% CI 0.73 to 2.26, p = 0.39, I²=0%). The diuretics group shows more significant SCr improvement (SMD = 0.23, 95% CI 0.08 to 0.38, p = 0.003, I²=41%), yet no significance Cystatin-C improvement (SMD = 0.21, 95% CI -0.02 to 0.43, p = 0.07, I²=0%). Conclusions There is no significant difference between ultrafiltration and loop diuretics to neurohormonal and kidney parameters change in type-1 CRS patients although loop diuretics administration shows more benefits. However, further trials are needed to establish the comparison.