The time dependence of the output of a high‐energy HCN laser has been studied with an indium antimonide detector. At a CH3CN partial pressure of 0.24 torr, three separate infrared pulses are emitted during a 250 &mgr;sec time interval after the current pulse. The addition of He, A, O2or H2changes both the number and delay between the pulses. As many as six pulses approximately 90 &mgr;sec apart in a 450 &mgr;sec period are observed with a He&sngbnd;CH3CN gas mixture.