The Kilimanjaro Altitude Research Expedition 2009 set out to investigate the epidemiology of Acute Mountain Sickness on Mount Kilimanjaro. The mountain is an extremely popular destination and so establishing the incidence and predictors of altitude sickness woudl be very useful. The expedition was generously supported by a grant from Chest Heart Stroke Scotland and was endorsed by Sir Chris Hoy, Reinhold Messner and the Mountaineering Council of Scotland. Led by Stewart Jackson, the team comprised of 5 other medical students at Edinburgh University: James Varley, Lucy Codrington, Claudie Sellers, Katherine Josephs and Georgina Duke.The team was split into two groups, each of which were based at different altitudes, and spent several weeks on the mountain, collecting data from hundreds of climbers attempting the summit. The data, which will be published later in the year by the Journal of High Altitude Medicine and Biology, revealed some important facts about the mountain. Firstly, we found that at the base camp (~4800m), at least 45% of climbers were suffering from Acute Mountain Sickness. Secondly, probably due to the extremely fast ascent on the mountain, our data suggests that acetazolamide may be less effective on the mountain than in other high altitude climbs. In addition, the extra 'rest day' that many climbers choose to take on the mountain (at great expense) was not sufficient to confer protection from Acute Mountain Sickness. However, consistent with previous research, climbers that had previously undertaken an acclimatisation trek were less likely to suffer from Acute Mountain Sickness. It is therefore advisable that climbers planning to attempt the summit of Mount Kilimanjaro refer to this guide before setting off on their ascent. The expedition would like to thank the numerous sponsors of the expedition, including Amazon Medical, Carters of Reading, Chest Heart Stroke Scotland, Edinburgh Rotary Club, Littmanns, The Medical Defence Union, The Medical Protection Society, Midsummer Energy, Mule Bars, Scottish International Education Trust, Sequal, Stuart Munro, Transglobe Expedition Trust and Wesleyan Medical Sickness. Thanks also to the Honest Kessy and his fantastic team of porters, cooks and guides.