Background Residual kidney function (RKF) is a dynamic marker having been shown to demonstrate fluctuations over successive days of the interdialytic interval. This study compares measured RKF between the long (LIDP) and short interdialytic intervals (SIDP). Methods This was a prospective cohort study. Thirty-four clinically stable, ambulatory facility hemodialysis patients were recruited. Urine samples collected in the last twelve hours of each interdialytic interval were paired with a blood test at the conclusion of each twelve-hour interval to evaluate measured RKF through a mean of urinary urea and creatinine clearances. The paired Student's t-test and the Wilcoxon matched-pairs signed-ranks were used respectively to compare differences in assessed mean and median RKF. Results Although average serum creatinine (607 +/- 219 µmol/L vs. 547 +/- 192 µmol/L, p = <0.01) and serum urea concentrations (25 +/- 15 mmol/L vs. 19 +/- 5 mmol/L, p = 0.01) were higher in the LIDP compared to SIDP, there was no statistically significant difference in urine volume (630 +/- 460 mL vs. 520 +/- 470 mL, p = 0.06), urine urea (116 +/- 49mmol/L vs. 118 +/ 90, p = 0.87), or urine creatinine (7816 +/- 3943 µmol/L vs. 8926 +/- 5752 µmol/L, p = 0.06) concentrations. On the whole, there was no significant difference in assessed RKF between the long and short interdialytic intervals (mean 8 +/- 6 mL/min vs 6 +/- 4 mL/min, p = 0.24; median 6.3 [3.2 - 10.4] vs 5.8 [3.8 - 8.9], p = 0.13). Conclusions There was no statistically significant difference observed in assessed RKF between the LIDP and SIDP. Measured RKF through samples collected from the LDIP and SIDP are comparable.