Background: Continuous renal replacement therapy (CRRT) technique may affect circuit lifespan. A shorter circuit life may reduce CRRT efficacy and increase costs. Methods: In a before-and-after study, we compared circuit median survival time during continuous venovenous hemofiltration (CVVH) versus continuous venovenous hemodialysis (CVVHD). We performed log-rank mixed effects univariate analysis and Cox mixed effect regression modeling to define predictors of circuit lifespan. Results: We compared 197 CVVHD and 97 CVVH circuits in 39 patients. There was no overall difference in circuit lifespan. When no anticoagulation was used, median circuit survival time was shorter for CVVH circuits (5 h, 95% CI 3–7 vs. 10 h, 95% CI 8–13, p < 0.01). Moreover, CVVHD, lower platelets levels, and longer activated partial thromboplastin time independently predicted longer circuit median survival time. Conclusions: CVVHD is associated with longer circuit median survival time than CVVH when no anticoagulation is used and is an independent predictor of circuit survival.