In the study presented here, another regression analysis formula was derived for calculating Kt/V from the pre- and post-dialysis Blood Urea Nitrogen (BUN). We prospectively compared the Kt/V values obtained using this new formula and the Kt/V values obtained via the other existing formulae to see whether reliance on the latter approach was more likely to lead to errors in over- or underprescribing dialysis regimens. Data were processed on 268 dialysis patients. The estimated Kt/V (Kt/VAzar) values were statistically different (p < 0.05) from the calculated Kt/V values from other models, except for those Kt/V values calculated according to the Lowrie (P = 0.112), Keshaviah (P = 0.069), Daugirdas First Generation (P = 0.059), Basile (P = 0.102), Ijely (P = 0.286) and Daugirdas Second Generation (P = 0.709). The best correlations were seen with the Daugirdas Second Generation formula (R = 0.958 and R² = 0.919). Since the best correlations were seen between Kt/VAzar and the Daugirdas Second Generation Kt/V we can demonstrate that these two models are perfect than the other models.