Methods of continuous renal replacement therapy (CRRT) in extracorporeal membrane oxygenation (ECMO) patients include dedicated central venous cannula (CVC) (vCRRT), in-series with filter connected to ECMO circuit (eCRRT) or in-line with haemodiafilter incorporated within ECMO circuit. We assessed the efficacy and safety of eCRRT versus vCRRT in 20 ECMO-CRRT patients. Average filter lifespan was 42 vs 28 hours and filter runs completing 72hours were 40% vs 13.8% (eCRRT vs vCRRT, respectively). One incidence of ECMO circuit air embolus occurred (vCRRT). eCRRT achieved adequate filtration and increased filter lifespan, and has become our default for ECMO-CRRT if a pre-existing dialysis CVC is not present.