An EEC Working Party has investigated death certification of respiratory disease in eight EEC countries by sending ten standard case histories to a sample of certifying doctors in each country. Results of interest to clinicians with reference to certification of farmer's lung, and of obstructive airway diseases, are presented. For a case of farmer's lung, a majority of certifying doctors in all countries certified an interstitial lung disease, but the proportion certifying farmer's lung ranged from 70% to 0% (overall 26%). Rural doctors certified farmer's lung more frequently than others only in some countries. For four cases of different types of airways disease (chronic obstructive bronchitis, emphysema or asthma) there were wide differences between countries of certification of these conditions or of unspecified chronic airways obstruction. Some countries certify more emphysema, and others, particularly younger doctors in English speaking countries, more unspecified chronic airways obstruction. There are also large differences in the certification of asthma. The differences are presumed to be attributable to differences of medical education. Epidemiological studies and patient care might be helped by more uniformity of diagnostic criteria within the EEC.