We carried out a comprehensive literature review of the medicinal use of palms in northwestern South America and complemented it with a large number of field interviews. We investigated patterns of medicinal use across three ecoregions (Amazon, Andes, Chocó), four countries (Colombia, Ecuador, Peru, Bolivia), and three human groups (indigenous, mestizos, and Afro-Americans). Overall, we reviewed 129 references with medicinal palm data and conducted 1956 field interviews, which yielded 93 medicinal palm species, 924 uses for the treatment of 157 diseases and ailments, and 1553 use-reports. The Amazon ecoregion showed the highest incidence of medicinal use, but overall use patterns were similar to those in the Andes and the Chocó. Ecuador was the most intensively studied country, whereas our fieldwork demonstrated that the Andes of all countries, and the Chocó of Colombia could still yield more information. The most common medicinal uses were associated to Digestive system, Skin and subcutaneous tissue, Infections and infestations, and Respiratory system. The medicinal use of palms was clearly more prominent among the indigenous than amongst mestizos and Afro-Americans. Medicinal palm use was not random, but rather showed similar patterns across ecoregions and countries, covering the livelihoods and needs of primary health care, often unmet by Western health systems.