Field enclosure measurements of a temperate forest soil show net uptake of ambient methyl bromide (CH3Br), an important trace gas in both tropospheric and stratospheric ozone cycling. The net flux for 1999 was estimated to be -168 ¿ 72 ¿g CH3Br m-2 (negative indicates loss from the atmosphere). Individual enclosure flux measurements ranged from -4.0 to +3.3 ¿g CH3Br m-2 d-1. Soil consumption of CH3Br was estimated from laboratory soil incubations. Production of CH3Br was calculated as the difference between net flux and predicted consumption. Fungi could be responsible for the production of CH3Br in this temperate forest soil.