The number of marketed non-steroidal anti-inflammatory agents varies widely from one European country to another, partly as a consequence of differing regulatory policies. During a four-year period, nine of 18 applications to market such drugs in the Netherlands failed; the remaining nine compounds were all licenced; in all, 22 single drug entities of this type are currently on sale. In Norway during the same period none of the 15 applications received was granted, though five cases are still pending; only seven such drugs are currently licenced for sale. The reasons for the national decisions and for the discrepancies between them are analyzed. A study of the prescribing practice of rheumatologists in the two countries suggests that some 10 to 15 products of this type are in fact needed in order to provide a reasonable choice. Current registration trends could markedly discourage further research investment in this field unless in the near future a basis is found for developing non-steroidal anti-inflammatory drugs with distinct advantages as compared with all those so far known.