Beijing successfully hosted the 2008 Olympic Games, and the services including medical services were widely appreciated by both participants and visitors. We retrospectively analyzed the quality of the medical services provided to athletes, spectators, VIPs, and the workforce during the Beijing 2008 Olympic Games. The information thus gathered would be useful for planning strategies for managing mass gatherings. Medical encounter forms filled during the Beijing 2008 Olympic Games were retrospectively reviewed. Descriptive statistics was used to characterize the data by accreditation and diagnostic categories. A total of 22 892 medical encounters were documented during the Beijing 2008 Olympic Games. Among them, 10 549 (46.08%) involved the workforce, 3 365 (14.70%) athletes, 3 019 (13.19%) spectators, 585 (2.56%) members of the media, 1 065 (4.65%) VIPs, and 4 309 (18.82%) others. Of the 22 892 cases, physical injury accounted for 27.90% (6 386), respiratory disease 18.21% (4 169), and heat-related illnesses 2.68% (615). Preparations of the medical service for the Beijing 2008 Olympic Games were made for 7 years, and the service provided has been praised worldwide. This study provides valuable information that may be useful for planning medical services for upcoming Olympic Games, including the London 2012 Olympic Games and other mass gatherings.