After long years of relatively passive behaviour, national libraries have reinvented themselves as user- friendly institutions, whose websites should play an important role in reaching a whole new audience. This article is based on the authors' findings of an evaluation of several European national library websites. While the survey showed that these websites are relatively good, there are still some minor points that need to be addressed. Several concepts and problems regarding national libraries and websites are discussed, in the light of usability and efficiency of library services. Particular emphasis is given to the problem of mission statements being reflected in a library's website. The marketing potential of websites is discussed in the light of the increasing accountability of national libraries and library performance evaluation. A variety of guidelines concerning websites in general and national library websites in particular is presented and the reasoning behind the inclusion of several key content-related elements of websites is also offered.