The D/H content of methane emitted from biomass burning was measured using samples of smoke collected from large-scale laboratory combustion experiments and from fires typical of slash burning of primary forest and of pasture burning in the Brazilian Amazon. In laboratory experiments, the mean &dgr;D of methane emitted from Pinus ponderosa needle combustion (&dgr;DCH4(bb)) was -233¿2?. In Brazilian fires, &dgr;DCH4(bb) was -210¿16?. The measured D/H of the fuel biomass ranged from -59 to -125? and indicated a significant hydrogen isotope fractionation (ϵBURND) during combustion. For the laboratory experiments, ϵBURND(=(D/H)CH4/(D/H)Biomass-1)1000=-124? and in the field studies, ϵBURND ranged from -130 to -180?. These results contrast those for &dgr;13C which showed no fractionation during combustion, consistent with earlier studies. The measurements presented here suggest that a relatively narrow range exists for the &dgr;D of CH4 emitted from biomass burning on a global scale and that &dgr;D is an independent tracer for atmospheric CH4. Combining &dgr;DCH4(bb)=-210? with literature values for the strength and &dgr;D of the major CH4 sources, we estimate a &dgr;D for the global CH4 source of -283¿13?. This result provides a constraint for the D/H kinetic isotope effect associated with removal of atmospheric CH4 by atmospheric hydroxyl radicals. ¿ 2000 American Geophysical Union