The family Marcgraviaceae has a Neotropical distribution (Caribbean, central and southern Mexico to Bolivia and southeastern Brazil). An analysis of morphological circumscription, distribution, and a checklist of this family are presented in this study in order to contribute to existing knowledge about Neotropical flora. A new synonym for Marcgraviastrum mixtum (Triana & Planch.) Bedell is proposed. The countries that present the greatest number of species for this plant family are Colombia (56 species), Brazil (39), Ecuador (36), Peru (30), Costa Rica (29), Panama (24) and Venezuela (24). In terms of endemic species, Brazil (15), Colombia (11), Costa Rica (6) and Ecuador (6) show the highest levels of endemism. Some new or unnoticed records for the floras of Brazil, Colombia and Peru are given; whereas some species are excluded from the lists of Brazil, Colombia, Costa Rica, Guyana and Panama. It was found that the Marcgraviaceae are more diversified in low and middle lands (0-1500 meters above sea level) (y = -0,034x + 105,5; R2= 0,937), and their major focus of diversity is located in northwestern South America (Colombia, Ecuador and Peru), with a second focus in Brazil. Thus, the family is currently recognized to have 8 genera and 136 species.