Background Ultrafiltration is not commonly used because of higher incidence of worsening renal function without improved decongestion. We examined differential outcomes of high versus low fluid removal and preserved versus reduced ejection fraction (EF) in CARRESS‐HF (Cardiorenal Rescue Study in Acute Decompensated Heart Failure). Methods and Results Baseline characteristics in the ultrafiltration arm were compared according to 24‐hour ultrafiltration‐based fluid removal above versus below the median. Patients were stratified by EF (≤40% or >40%). We compared clinical parameters of clinical decongestion during the hospitalization based on initial (≤24 hours) response to ultrafiltration. Cox‐proportional hazards models were used to identify associations between fluid removal <24 hours and composite of death, hospitalization, or unscheduled outpatient/emergency department visit during study follow‐up. The intention‐to‐treat analysis included 93 patients. Within 24 hours, median fluid removal was 1.89 L (Q1, Q3: 1.22, 3.16). The high fluid removal group had a greater urine output (9.08 versus 6.23 L, P =0.027) after 96 hours. Creatinine change from baseline to 96 hours was similar in both groups (0.10 mg/dL increase, P =0.610). The EF >40% group demonstrated larger increases of change in creatinine ( P =0.023) and aldosterone ( P =0.038) from baseline to 96 hours. Among patients with EF >40%, those with above median fluid removal (n=17) when compared with below median (n=17) had an increased rate of the combined end point (87.5% versus 47.1%, P =0.014). Conclusions In patients with acute heart failure, higher initial fluid removal with ultrafiltration had no association with worsening renal function. In patients with EF >40%, ultrafiltration was associated with worsening renal function irrespective of fluid removal rate and higher initial fluid removal was associated with higher rates of adverse clinical outcomes, highlighting variable responses to decongestive therapy.