A new species is recognized here as part of the taxonomic revision of the Polygalaceae in southern Brazil. Polygala densiracemosa Lüdtke & Miotto belongs to Polygala L. subg. Polygala, which comprises around 88 species and 22 varieties in Brazil, being the best represented subgenus of Polygala in the Brazilian flora. Polygala densiracemosa can be confused with P. campestris Gardner and P. linoides Poir. by the resemblance of the flowers, fruits, and seeds and by the similar geographical distribution. However, P. densiracemosa is distinguished by a generally caespitose habit and dense racemes. The new species is described and illustrated, observations on habitat and distribution are provided, and differences among related taxa are discussed.