The relative economic importance of quality traits in ostrich feathers. The prices obtained for 222 repeatedly evaluated single ostrich feathers and 498 feather-lots sold at 11 auction sales during 1978 and 1979, were used to determine the relative economic importance of 23 feather quality traits by means of partial regression coefficients. Although the normal process of supply and demand may result in small price fluctuations between auctions, a clear pattern exists with regard to the main components of overall excellence upon which buyers regularly base their feather prices, namely feather size, appearance, flue quality and weathering. Of these, feather size, appearance and flue quality are the most important quality traits. Price differences between feathers at the same auction, as well as between auctions, rather reflect the actual differences in quality between feathers. Thus feather size, feather appearance and flue quality had the greatest effect on long-term price determination. Owing to the method of price determination used by various buyers with regard to first-choice feather traits, it seems unnecessary to make provision for fashion differences between the manufacturers. In the different feather price categories, shortcomings in the classing of feathers indicate that those with the first-choice traits do not always command the highest prices. Feather size and appearance should be accepted as a basis for classing and sorting of feathers, with further emphasis on quality deviation and colour faults, thereafter.