Background. Accurate evaluation of physical function in patients undergoing haemodialysis is crucial in the analysis of the impact of exercise programs in this population. Objective. To evaluate the reproducibility of several physical functional tests, depending on the timing of their implementation (before the HD session versus non-HD days). Design. Prospective, non-experimental, descriptive study.Methods. Thirty patients in haemodialysis were evaluated twice, one week apart. The test session was performed before the haemodialysis session started and a retest was performed in non-dialysis day. The testing battery included the Short Physical Performance Battery, sit-to-stand-to-sit tests, six-minute walking test, one-leg stand test, timed up and go, and handgrip strength with and without forearm support. The intra- rater reproducibility was determined by the intraclass correlation coefficients and the agreement was assessed by Bland–Altman analysis.Results. The interclass correlation coefficients values ranged from 0.86 to 0.96, so that all tests showed good to very good relative reliability. The mean differences between trials of sit to stand to sit 10 and 60, Time up and go and all the handgrip tests were close to zero, indicating no systematic differences between trials. Large range of values between trials was observed for the Six minutes walking test, gait speed, One-leg stand test and Short physical performance battery, indicating a systematic bias for these four tests.Conclusion. The Sit to stand to sit 10 and 60, time up and go and handgrip tests had good to excellent test-retest reliability in measuring physical function in different dialysis days of patients undertaking haemodialysis. The Minimal detectable change values are provided for this population. Bias were found for the Six minutes walking test, gait speed, Short physical performance battery or one-leg stand test when the testing day changed.