When an extrinsic, direct band‐gap semiconductor sample is irradiated by photons of an energy higher than the energy of the band gap between valence and conduction bands, excess electron‐hole pairs are generated which, while diffusing through the sample, produce luminescence via radiative recombination. If, furthermore, the intensity of the impinging beam of photons is modulated sinusoidally, the luminescence radiation escaping from the sample will be phase shifted with respect to the original photon beam in a characteristic way. It will be shown that by measuring the phase shift at different modulation frequencies, the Shockley‐Read‐Hall lifetime of minority carriers may be ascertained. The method is nondestructive inasmuch as there is no need to fabricatep‐njunctions or Ohmic contacts, nor is it necessary to remove already existing Ohmic contacts or angle lap the surface, etc., procedures often needed when determining lifetimes with the scanning electron microscope (in which case ap‐njunction must be present).