We have measured bromoform (CHBr3) in the troposphere and lower stratosphere (sea level to 17 km) from balloons, aircraft and ground stations. The concentrations ranged from 2 to 20 ppt at sea level, and 0.1 to 1 ppt in the upper troposphere. Above the tropopause the concentrations declined sharply to less than 0.01 ppt above 14 km. CHBr3 accounted for 3% of total measured organic bromine (Br0) at the extratropical tropopause, and appeared to potentially contribute at least 9% of reactive bromine (Bry) in stratospheric air of mean age less than 1 year. Inclusion of dibromomethane and the mixed bromochloromethanes increased these figures to about 10% of Bro and 20% of Bry respectively. Observations of CHBr3 in both Arctic and midlatitudinal stratospheric air, and in air masses with mean ages of more than 1.5 years, suggests that the CHBr3 in these locations originates predominantly from extratropical stratosphere-troposphere exchange.