Plant parasitic nematodes associated with roots of 71 weed plant species were collected from selected cultivated areas of Brazil. Eight genera and 18 species of plant parasitic nematodes were reported. The species were recovered in the following decending order of frequency: Helicotylenchus dihystera (46%); .Meloidogyne javanica (24%); Meloidogyne incognita (23%) ; Macroposthonia ornata (17%) ; Pratylenchus brachyurus (16%); Pratylenchus zeae (14%); Xiphinema, setariae (11%); Xiphinema krugi (10%); Helicotylenchus pseudorobustus (5.6%); Meloidogyne arenaria (4.2%) ; Helicotylenchus dihysteroides (4.2%) ; Tylenchorhynchus martini (4.2%) ; Aphelenchoides sp. (2.8%); Ditylenchus sp. (2.8%); Helicotylenchus microcephalus (2.8%); Xiphinema elongatum (2.8%) ; Helicotylenchus egyptiensis (1.4%) ; and Meloidogyne coffeicola (1.4%). Considerations were given to the agricultural production implications of the wide distribution of nematodes associated with weed plants and pasture grasses.