A taxonomic revision of the endemic Malagasy genus Helmiopsis H. Perrier (Malvaceae s.l.) is presented, based on material that has been collected since the last complete revision by Arènes. Nine species and one subspecies are recognized, of which one species (H. polyandra Appleq.) and one subspecies (H. hily Arènes subsp. boinensis Appleq.) are newly described from Madagascar. Arènes' infrageneric taxonomy is simplified; two sections (section Glandulipetalae Arènes and section Helmiopsis) are recognized. The section Glandulipetalae is typified by H. pseudopopulus (Baill.) Capuron ex Arènes, and H. inversa H. Perrier, the type species for the genus, is lectotypified. Dombeya rigida Baill. is excluded from Helmiopsis. Preliminary conservation assessments using IUCN criteria indicate that most taxa are of potential conservation concern: four species native to the extreme north should be considered Vulnerable, and one species and one subspecies are considered Data Deficient but likely to be at risk.