Objectives To evaluate the nursing workload related to two techniques of continuous renal replacement therapy. Research methodology We analysed retrospectively the nursing work load caused directly by continuous renal replacement therapy in a cohort of patients admitted consecutively over 10 months. Two types of continuous renal replacement therapy have been compared: dialysis with regional citrate anticoagulation and haemodiafiltration with systemic heparin coagulation. Setting Academic Hospital Intensive Care Unit. Main outcome measures The nursing workload was defined by the time spent in the management of continuous renal replacement therapy, including preparation of the circuit and related biological controls. Results 60 patients underwent a total of 202 sessions of continuous renal replacement therapy. The nursing workload as expressed as % time of nursing care was similar (12.3 [9.4–18.8] vs 13.4 [11.7–17.0] %, for haemodiafiltration and dialysis respectively, P = 0.06). However, the distribution of the nursing workload is different: the bigger proportion of care is circuit preparation in haemodiafiltration and biology control in dialysis. Conclusions Nursing time dedicated to continuous renal replacement therapy is similar whatever the renal replacement therapy technique. However, a longer duration of the filter and a better circuit predictability with dialysis and citrate anticoagulation are potential benefits for nursing workload.