PassiveQswitching of a flashlamp‐pumped alexandrite laser with a Cr4+:Y2SiO5(Cr4+:YSO) solid‐state saturable absorber has been demonstrated at room temperature. An output of a singleQ‐switched laser pulse of 20 mJ in energy and 70 ns in duration was obtained. The output wavelength of theQ‐switched laser pulse and the free‐running laser was 753 nm. ©1995 American Institute of Physics.