In this third article on the role of international comparative practices in the formation of national health care systems I discuss a familiar group of systems-builders--medical professional organisations--and so focus on some early comparisons undertaken by organised groups of doctors. So far in this series I have argued that any attempt to make international comparisons--whether in the 19th-century or today--is bound to be based on a 'characteristically national' understanding. Not infrequently such an understanding finds its clearest expression in the very (...) act of undertaking practical tasks like 'comparing'. Dependent on whether comparisons are carried out by individuals privately, collectively by larger groups within the medical profession, or by government agencies the descriptions of 'national characteristics' (of medical organisation, institutional formation, clinical practice, research, public health and education) will differ in emphasis. -/- The examination of collective professional attempts at international comparison can enhance our understanding of the cultural distinctions that were incorporated by emerging national medical professions. This process can show which aspects of foreign medical systems were deemed pertinent, and also reveals methodology. What did such collective endeavours add to the more biographically coloured comparisons undertaken by the individual mid-century authors I discussed in part II of this series? (shrink)