The genus Adelogorgia is distinguished from other holaxonians in having conspicuously ornamented double-disc sclerites and leaf clubs in the coenenchyme, and non-mineralised axis cores. The two eastern Pacific species currently recognised as Adelogorgia are diagnosed and illustrated. Three new species for the genus are described from new localities and depth ranges. Analysis of external and internal characters, especially sclerite colours and sizes, and colony colour, shape and branching, allows separating the species. An identification key to the five species is provided, as well as a character table for comparisons. This study was based on newly collected specimens from 50 to 200 m deep, and re-examination of all historical material. We conclude that the genus comprises five valid species with a wider distribution than previously reported. This research is a contribution to the octocoral systematics and biodiversity from mesophotic and deep waters.