We report Shockley–Read–Hall (SRH), radiative, and Auger recombination rates in midinfrared laser structures from time-resolved photoluminescence using frequency upconversion. The devices studied were actual InAsSb/InAlAsSb multiple-quantum-well (MQW) diode lasers emitting near 3.3 μm, which have been previously characterized for laser performance. We extend the initial studies and report on the carrier recombination dynamics. The importance of carrier density motivates a careful examination of carrier density and quantum-well effects. SRH, radiative, and Auger recombination rates (ASRH, Brad, and CAuger, respectively) were measured at 77 K and found to be ASRH−1 ≈ 10 ns, Brad ≈ 2×10−10 cm3 s−1, and CAuger ⩽ 1.0×10−29 cm6 s−1, respectively. At 150 K the nonradiative recombination coefficients increased to ASRH−1 ≈ 1.7 ns, Brad ≈ 0.78×10−10 cm3 s−1 and CAuger ≈ 7.0×10−28 cm6 s−1, respectively. This study suggests InAsSb/InAlAsSb MQW diode laser performance may be limited by SRH nonradiative recombination mechanisms rather than Auger recombination. © 1998 American Institute of Physics.