There is a wide variation in the mortality from asthma between the countries of the European Community. Studies using a standard case history of a typical asthmatic to assess death certification practice have suggested that this variation is not related to the ways that doctors fill out death certificates. Reanalysis of the data from one of these studies suggests, however, that the way doctors certify more ambivalent case histories may explain much more of the variation. Repetition of this study in a small group of French and English doctors with a special interest in asthma came to the same conclusion, suggesting that these differences are due to both a genuine difference in nosology between the countries as well as to the quality of death certification.