Numerous studies have identified a strong linkage between the delivered dialysis dose (Kt/V) and the survival of hemodialysis (HD) patients. However, the current method used to calculate Kt/V requires multiple blood samples and the process is complex and time consuming. We evaluate the performance of a recently developed on-line monitor (Biostat 1000 dialysate urea monitor, Baxter) that measures the urea concentration in the effluent dialysate and displays Kt/V and nPCR immediately after hemodialysis. To verify the performance of the urea monitor, we selected 21 hemodialysis patients, calculated their Kt/V and nPCR values from blood samples obtained during each hemodialysis, and compared the results with data obtained using the urea monitor. The Kt/V and nPCR values calculated by the urea monitor were both significantly correlated with those obtained using blood samples (R = 0.804, p < 0.001 in Kt/V and R = 0.749, p < 0.001 in nPCR). Our results suggest that the urea monitor may be used for on-line assessment of dialysis adequacy and obviates the need for blood sampling.