Laser action at 2.7 &mgr; from atomic bromine was produced by flash photolysis of gaseous iodine monobromide. The output consists of a series of sharp pulses having peak powers up to 50 W and a total duration of 5 &mgr;sec. Optical gain was estimated to be ∼1 dB/m. Chemical reversibility of the system is very good; regeneration of the starting material occurs spontaneously and requires about 3 msec. The fact that excited bromine rather than excited iodine atoms are formed leads to clarification of previous conflicting spectroscopic assignments.