Vegetational changes were measured after 27 prescribed burns and 3 wildfires which occurred from 1982 to 1995 on buffelgrass pastures highly infested with brush in Sonora, Mexico. Densities of most undesirable brush species were reduced from 40 to 60% with fire. When prescribed burns occurred in good rainfall years the buffelgrass forage production exceeded (1.4 to 2.3 tons/Ha) that of unburned areas for three consecutive growing seasons after a single burn. Similar forage increases were also evident on pastures accidentally burned either once, twice or three times during alternated years. However, during dry growing conditions, less (1.2 tons/ha) buffelgrass forage was produced on burned than on unburned areas.