A study of the diversity of legumes in the northern part of the state of Nuevo León was undertaken. 38 genera, 94 species and 26 infraspecific taxa of legumes were recorded. The family Fabaceae comprises 18 genera and 42 species, Mimosaceae 10 and 30 and Caesalpiniaceae 10 and 22 respectivelly. The genera with highest number of species are Acacia (12), Dalea (10), Mimosa (6), Senna (5), Caesalpinia (4) and Bauhinia (4). Shrubby legumes are the most abundant in the zone, representing 47% (46 species); the herbaceous ones constitute 46% (45) and the arboreal ones comprise 7% (7). The highest number of taxa was recorded on semithorn shrubland (52) piedmont scrub (48), oak-pine forest (44), while the mezquite shrublands shelter the lowest number of species (23).