Transversely excited atmospheric (TEA) CO2laser ablation of boron nitride ceramics in both cubic and hexagonal phases (cBN, hBN) was demonstrated. A TEA CO2laser oscillating at a wavelength of 9.2 &mgr;m, which coincides with a TO‐phonon spectrum of the cBN, could ablate the cBN ceramics more efficiently than with 10 &mgr;m band radiation. The hBN samples were also ablated well with 9.2 &mgr;m laser irradiation, however, the ablated site color changed to black due to a boron rich phase left on the surface. In the case of hBN sintered with Al2O3and SiO2, the ablation threshold fluence is determined by the one of Al2O3, which is the highest threshold among the three elements. ©1996 American Institute of Physics.