The survey was undertaken by ESWI in order to investigate the comparability of the laboratory diagnostic methods and the influenza surveillance systems used in 24 European countries. The results indicate considerable consensus in the general approaches to collection and use of clinical specimens, rapid diagnostic techniques, virus isolation techniques in eggs or/and MDCK cell lines, virus identification and use of inhibition of hemagglutination (IHA) and complement fixation (CF) tests for serological diagnostics. However, the details of the techniques used are somewhat heterogeneous: antigen detection methods (immunofluorescence versus immuno adsorbent assay), isolation methods (eggs versus tissue culture), reagents (locally produced, WHO, commercial) are not always equivalent and results are therefore not really comparable. Some of these discrepancies are due to a lack of resources or a lack of priority for influenza in the country. The greatest differences between individual countries exist in the epidemiological part of surveillance programmes. The mode of collection of influenza related mortality and absentism from work varies considerably in different countries. These findings indicate the need to harmonize viral procedures and surveillance systems in European countries in order to improve validity and comparability of results and as a prerequisite for early information on influenza etiology and spread.