Water table position, through the creation of aerobic and anerobic conditions in the soil profile, plays an important role in controlling CH4 flux from wetlands. A laboratory study of peat columns revealed that CH4 emission rates initially increased and then decreased as the water table was lowered from the peat surface to a depth of 50 cm, with the release of CH4 trapped in pores. There was a strong hysteresis between CH4 flux on the falling and rising water table limbs (falling>rising). When expressed as seasonal average values, there was a strong relationship (r2 0.08--0.74) between log CH4 flux and water table position for sites within 5 wetland regions in boreal-subarctic Canada. The regression coefficients were similar among regions (0.022--0.037), but there were differences in the regression constants (0.47--1.89 ). CH4 flux from drained, forested peatland soils decreased as the water table depth increased, and several sites were transformed from sources to sinks of CH4. Global CH4 emissions to the atmosphere may have been reduced by ≈1 Tg yr-1 by peatland drainage during the last 100 yr. ¿American Geophysical Union 1993