While larger British colonies in Africa and Asia generally had their own medical services, the British took a different approach in the South Pacific by working with other colonial administrations. Together, colonial administrations of the South Pacific operated a centralised medical service based on the existing system of Native Medical Practitioners in Fiji. The cornerstone of this system was the Central Medical School, established in 1928. Various actors converged on the school despite its apparent isolation from global centres of power. It was run by the colonial government of Fiji, staffed by British-trained tutors, attended by students from twelve colonies, funded and supervised by the Rockefeller Foundation, and jointly managed by the colonial administrations of Britain, Australia, New Zealand, France and the United States. At the time of its establishment, it was seen as an experiment in international cooperation, to the point that the High Commissioner for the Western Pacific called it a ‘microcosm of the Pacific’. Why did the British establish an intercolonial medical school in Oceania, so far from the imperial metropole? How did the medical curriculum at the Central Medical School standardise to meet the imperial norm? And in what ways did colonial encounters occur at the Central Medical School? This article provides answers to these questions by comparing archival documents acquired from five countries. In doing so, this article will pay special attention to the ways in which this medical training institution enabled enduring intercolonial encounters in the Pacific Islands.