Calathea hylaeanthoides Kennedy, Calathea retroflexa Kennedy, and Calathea incompta Kennedy are described as new. All three species are endemic to Costa Rica. Calathea hylaeanthoides and C. incompta are from the Osa Peninsula, while C. retroflexa is from midelevation on the Pacific slope of the Cordillera de Talamanca. Calathea hylaeanthoides belongs to Calathea section Breviscapus, C. retroflexa belongs to Calathea section Calathea, and C. incompta belongs to the "Ornata group" of Calathea. Key words: Marantaceae, Calathea, Costa Rica, endemism.