Recent advances in body-worn sensor technology have increased the scope for harnessing quantitative information from the timed-up-and-go test (TUG), well beyond simply the time taken to perform the test. Previous research has shown that the quantitative TUG method can differentiate fallers from non-fallers with greater success than the manually timed TUG or the Berg Balance Test. In order to advance this paradigm of falls risk estimation it is necessary to investigate the robustness of the quantitative TUG variables. This study investigated the inter-session and intra-session reliability of 44 quantitative TUG variables measured from the shanks and lower back of 33 study participants aged between 55-65 yrs. For intra-session reliability, 25 variables demonstrated excellent reliability (ICC>0.75), and 12 demonstrated "fair to good reliability" with ICCs between 0.4 and 0.75. Analysis of test-retest reliability resulted in ICC > 0.75 for 18 out of 44 variables, with 20 variables showing fair to good reliability. Turn time parameters demonstrated poor reliability. We conclude that this is a reliable instrument that may be used as part of a long-term falls risk assessment, with further work required to improve certain turn parameters.