A key parameter in any discussions about the academic peer reviewed journal system is the number of articles annually published. Several diverging estimates of this parameter have been proposed in the past, and have also influenced calculations of the average production price per article, the total costs of the journal system and the prevalence of Open Access publishing. With journals and articles increasingly being present on the web and indexed in a number of databases it has now become possible to quite accurately estimate the number of articles. We used the databases of ISI and Ulrich's as our primary sources and estimate that the total number of articles published in 2006 by 23 750 journals was approximately 1 350 000. Using this number as denominator it was also possible to estimate the number of articles which are openly available on the web in primary OA journals (gold OA). This share turned out to be 4.6 % for the year 2006. In addition at least a further 3.5 % was avail...