Background: muscle mass (MM) plays an important role in the physical function of hemodialysis patients; However, muscle mass measurement can be unreliable and expensive. In contrast, the measurement of physical function (PF) is simple and inexpensive and may serve as an alternative. The aim of this study was to correlate the measurement of MM by computed tomography (CT) with physical function measurements and physical activity (PA) levels in HD patients. Methods: this was a cross-sectional study that included 38 HD patients from a single HD clinic. Each participant had a CT scan to measure mid-thigh muscle mass. Physical function tests were assessed using the six-minute walk test (SMWT), handgrip strength (HGS) test, 5 x sit-to-stand test (STS5), timed up and go test (TUGT) and Short Physical Performance Battery (SPPB). ), while physical activity levels were measured using the Godin-Shephard leisure-time physical activity questionnaire. Correlation analysis was used to examine the relationship between variables. Results: handgrip strength was strongly positively correlated with thigh muscle area (r = 0.656, p ≤ 0.001) and weakly correlated with arm muscle area (r = 0.396, p = 0.002), SMWT (r = 0.373, p = 0.004), SPPB (r = 0.269, p = 0.041) and physical activity (r = 0.323, p = 0.013). There was also a trend for an inverse correlation between handgrip strength and TUGT (r = -0.235, p = 0.076). Positive correlations were found between the thigh muscle area and the SPPB (r = 0.339, p = 0.009) and PA (r = 0.293, p = 0.025), while there was a trend for an inverse correlation between thigh muscle area and STS5 (r = -0.256, p = 0.052). Conclusion: several measures of PF and strength were correlated with objective measurements of MM, thus providing options for low-cost measurements related to muscle mass.