Residues of glyphosate (N-phosphonomethylglycine) and its metabolite aminomethylphosphonic acid (AMPA) were followed on three forested sites in Oregon, Michigan, and Georgia. Eight-hectare residual stands of low-quality hardwoods were treated with 4.12 kg/ha glyphosate ae applied aerially in late summer. Residues were highest in upper crown foliage. Overstory reduced exposure of understory vegetation and streams. Residues in streams were close to the detection limit or undetectable in 3-14 days. Residues in soils were highest where cover was sparse and where litter was removed. No residues were detectable in soil 409 days after treatment; movement below 15 cm was negligible. AMPA appeared at low levels in all degrading matrices, including sediments, soon after deposition of glyphosate