Empirical Research Background: Traditional approaches to physical fitness assessment have two major deficiencies: the first, the high dependence on raw scores limits the validity and accuracy of the interpretation of assessment results because raw scores are not valid ―measures‖ with inferential value; the second, students have to attempt all of the separate fitness indicators in order to get the whole picture about their abilities on the different components of physical fitness. Empirical Research Aims: This study aimed to explore a new approach to physical fitness measurement by developing a Rasch Measurement Physical Fitness Scale (RMPFS) consisting of the physical fitness indicators routinely used in Hong Kong primary schools. Empirical Research Sample: Data used in this study were retrieved from the database of a Hong Kong primary school covering primary students‘ physical fitness data over academic years 2002-03 to 2006-07. Empirical Research Method: Students‘ performances on 9 physical fitness indicators, i.e, BMI, 6-minute Run, 9-minute Run, 1-minute Sit-ups, Standard Push-ups, Modified Push-ups, Sit-and-Reach, Right Handgrip, and Left Handgrip, were analyzed with WINSTEPS 3.0. The partial credit model was specified for the analysis. The fitness indicators were investigated one by one from a Rasch measurement perspective. Empirical Research RASCH: The scale development was guided by Rasch measurement principles. The fitness indicators that violated Rasch measurement requirements would be excluded from the scale. Empirical Research Results: 1) A RMPFS which integrates three components of physical fitness including cardiorespiratory fitness, muscular endurance, and muscular strengthen was successfully developed; 2) The RMPFS and its scale indicators showed fit to the Rasch model sufficient for the intended purposes of measuring overall fitness of children. Empirical Research Conclusions: The findings of this study will be informative to physical education