Farmers stock peanuts, bulk stored inside large warehouses, were fumigated 24 hr with methyl bromide (bromomethane) after thorough sealing of the facilities. Temperature of the peanuts varied from 21.8 degrees to 26.8 degrees C and gas concentrations monitored in the headspace above the peanuts decreased from 20.1 to 12.2 mg/liter during fumigation. Gas concentrations in the mass varied considerably during fumigation, being highest at the bottom of the peanuts. Gas concentrations decreased to less than 1 mg/liter after 48 hr of aeration. Although tremendous populations of insects existed before fumigation, no insects survived the treatment. Bromide residues were much below the tolerance on the peanuts, although loose shelled kernels accumulated slightly higher residues than did sound mature kernels from pods. The success of the fumigation was attributed to the good construction of the warehouses and to the thorough sealing performed before the fumigation.