We present a new method for measuring time‐resolved photoluminescence on a time scale of microseconds and milliseconds using correlational analysis, and we demonstrate it to work on porous silicon and GaP:Fe. We modulate the pumping laser with a pseudorandom binary sequence which yields correlational properties similar to white noise. The photoluminescence decay is computed via cross correlation of the detector signal with the pumping sequence. The presented method is highly sensitive, simple in application, and inexpensive.