There are only two genera of the Aristolochiaceae, Aristolochia and Thottea, so far known to occur in Malesia. In the course of a revision of this family for the Flora Malesiana, some new species of both genera have been found. Eight new ones of Thottea were published in a precursor on that genus (Blumea 27, 1981, 301-332, f. 1-72). There are four new species of Aristolochia from Borneo and one more new Thottea from Sumatra to be described here.