The work that Physicians perform represents major resource input to medical services and procedures. In this article we describe the concepts of work and its dimensions, as well as the methods that measure total work which includes intra-service work and pre-/ post-service work We also present the survey results of physicians in internal medi-cine and general surgery for selected services. Our findings indicate that physicians can give reliable and valid ratings of work and that we can model this work as a function of four dimension: time, mental effort and jud-gement, technical skill and physical effort, and Analyzing the complex functional relationship between work and these four dimensions show that all four dimensions are import and statistically significant in predicting work. Technical skill and physical effort is a more important dimension in predicting work. Finally we found that an exponential equation of the four dimensions precisely describes work.