A taxonomic revision of the genus Acaena in Chile was carried out, using morphological characters. Twenty species belonging to six sections are recognized for continental Chile and Juan Fernandez Archipelago. The most useful characters for recognizing species are inflorescence type, the form of leaflets, as well as the form and ornamentation of the fruit. The following species are lectotypified: A. alpina Poepp. ex Walp., A. caespitosa Gillies ex Hook. et Arn., A. integerrima Gillies ex Hook. et Arn., A. macrocephala Poepp., A. magellanica (Lam.) Vahl, A. pinnatifida Ruiz et Pav., A. platyacantha Speg., A. splendens Hook. et Arn., and A. tenera Alboff. The following species were neotypified: A. lucida (Aiton ) Vahl, A. sericea J. Jacq., and A. trifida Ruiz et Pav. var. glabrescens Regel et Körn. The following synonyms were lectotypified: A. argentea Ruiz et Pav. var. breviscapa Bitter, A. argentea Ruiz et Pav. var. coriacea Bitter, A. argentea Ruiz et Pav. var. interrupte-pinnata Bitter, A. argentea Ruiz et Pav. var. lanigera Bitter, A. argentea Ruiz et Pav. var. subcalvescens Bitter, A. cadilla Hook. f., A. canescens Phil., A. cuneata Hook. et Arn., A. digitata Phil., A. digitata Phil. var. latifoliolata Bitter, A. digitata Phil. var. subpinnata Bitter, A. euacantha Phil., A. fuegina Phil., A. glandulifera Bitter, A. grandistipula Bitter, A. hirsuta Phil., A. ischnostemon Bitter, A. krausei Phil., A. krausei Phil. subvar. glabratula Bitter, A. longiaristata H. Ross [= A. magellanica (Lam.) Vahl], A. lucida var. villosula Bitter, A. macrostemon Hook. f. subsp. longiaristata (H. Ross) Bitter var. basipilosa Bitter, A. macrostemon Hook. f., A. magellanica (Lam.) Vahl subsp. pygmaea Bitter, A. magellanica (Lam.) Vahl var. glabrescens Bitter, A. microcephala Schltdl., A. multifida Hook. f. subsp. intercedens Bitter, A. neglecta Bitter, A. petiolulata Phil., A. pinnatifida Ruiz e