The present paper is the first of a series of revisions of the genera of Loganiaceae represented in Continental Africa. A genus is entirely revised only if the majority of the species occurs in Africa; if a small number of species is present only African representatives are taken into account. The delimitation of the family of Loganiaceae is a much debated problem. The present author so far prefers to follow Solereder (1892) and Bruce & Lewis (1960), but is of the opinion that Retzia which usually has been treated as an aberrant Solanacea belongs also in this family. After further study of the several genera constituting Loganiaceae, their relationship may become better understood and the family be delimited more satisfactorily. Gaertnera, generally regarded as a Rubiacea, related to Psychotria, is not accepted as Loganiaceous here.