Alstonia R.Br. (Apocynaceae) is a pantropical genus occurring in Africa, India, Indo-China, Southeast Asia, Malesia, Australia, and eastwards to the Marquesas Islands and Central America. In the framework of the International MOF Tropenbos Kalimantan Project, a revision of the genus is in progress. Alstonia comprises six sections and about 45 species. One new species from Irian Jaya, Indonesia is described here.