The article attempts to measure and report the extent and magnitude of shadow economy in Greek physicians’ sector. Tax evasion of self-employed doctors as well as informal payments to doctors in public health structures are identified as the two main parameters of shadow economy in this sector. This research attempts to create a standard multidimensional methodological model of approach and analysis of the shadow economy in physicians’ sector. This multidimensional model applied in Greece includes two phases of development of the research tools used. In the first phase, the level of tax evasion of self-employed doctors was assessed with a specific innovative methodology based on the following. Household expenditures for services of private doctors for the period 2011–2017 were analysed using data from the annual ‘Household Budget Survey-(HBS)’ of the Greek Statistical Authority and were compared with the financial data of the ‘Statistical Business Register-(SBR)’, which is updated with data from the Hellenic Tax Authority. In the second phase, the amount of ‘informal payments’ to doctors of the public sector was determined for the period 2011–2017. The survey made use of the HBS data on household expenditure for public care, which were compared with the revenue of public hospitals from private patients.