haemodiafiltration (hdf) techniques with high convective volumes are an interesting form of filtering due to their approximation to the native kidney. among them, post-dilution on-line hdf is the most efficacious form of infusion for eliminating molecules with different molecular weights. recent advances in technology permit the automatic prescription of the infusion flow (qi), proving at least as efficacious as manual infusion. the aim of this study is to assess whether it is possible to increase the efficacy of automated infusion in post-dilution on-line hdf by manually increasing the initial qi by measuring the final convective volume and kt. the nursing workloads are also assessed, measured by the number of interventions related to the technique. in all patients (n 96) 3 dialysis sessions are carried out (st 5008 fresenius medical care) with automatic reinfusion, followed by another 3 sessions with manual automated reinfusion increasing the qi by 10 ml/min to the automatically measured dose. the results obtained show significant differences (p<0.001) in the reinfusion volume, which is 6% higher in manual automated form (23.01 ± 2.22 litres) than in automated (21.7 ± 2.62 litres). 75% of patients reached 20 litres or more with self-replacement, compared to 87.5% with manual automated replacement (p<0.001). there are no differences in qb, qd, effective dialysis time and kt. the number of interventions due to alarms related to the technique or nursing staff is higher (p=0.001).