Ensuring a reliable and affordable supply of essential drugs to health facilities is one of the main challenges facing developing countries. This paper describes the revolving drug fund in Khartoum, which was set up in 1989 to improve access to high quality drugs across the State. An evaluation in 2004 showed that the fund has successfully managed a number of threats to its financial sustainability and has expanded its network of facilities, its range of products and its financial assets. It now supplies essential drugs to 3 million out of the 5 million population of Khartoum each year, at prices between 40% and 100% less than alternative sources. However, results illustrated the tension between achieving an efficient cost-recovery system and access for the poorest.