Based on morphology, a cladistic analysis of the Neotropical family Quiinaceae (Malpighiales) was performed to generate a hypothesis of the phylogenetic relationships within the family. The monotypic Medusagynaceae and four species of Ochnaceae were used as outgroup. Using equal weights, the Quiinaceae find strong jackknife support and all genera, apart from Lacunaria. are monophyletic. Lacunaria receives support only after successive weighting, The Lacunaria oppositifolia and Quiina pteridophylla are positioned within their respective genera, although separation of the former as monotypic cannot be discarded with certainty. Proposed close relationship of the two species is rejected. Froesia is the morphologically midst distinguished genus and sister to all other taxa of the family. Touroulia amazonica, once suggested to be recognized at the generic level, forms a small but closely related clade with T. Quiina is the most diverse and derided genus with highly unresolved relationships and numerous polymorphic characters. A reduction toward smaller inflorescence, and flowers, fewer stamens. and fewer carpels can be hypothesized. Concerning the evolution of sex distribution, androdiocy was fixed early in a common ancestor of Lacunaria. Quiina. and Touroulia, and subsequently dioecy evolved in Lacunaria. (Less)