Third‐order optical nonlinearities and recombination processes of photoexcited electron‐hole plasma in PbSe and PbTe are directly monitored by picosecond pump‐probe experiments in the wavelength range from 3 to 10 &mgr;m. After excitation, a strong blue shift of the absorption edge and large changes of the refractive index are found. Time‐resolved studies of the absorption changes at lattice temperatures between 70 and 160 K reveal a fast partial decrease of the carrier density within 100 ps at excitation densities exceeding 7×1017cm−3. Comparative emission spectra demonstrate that this behavior is due to recombination by stimulated emission. At room temperature the nonradiative Auger recombination dominates on a 0.5–2 ns time scale below the threshold of stimulated emission. The overall Auger coefficients for carrier densities of about 1018cm−3are derived from the data and have values ofcAPbSe=1.1±0.3×10−28cm6/s andcAPbTe=2.5±1.3×10−28cm6/s. ©1995 American Institute of Physics.