In this work we investigate the use of low-frequency noise (LFN) spectroscopy as a sensitive tool for investigation of semiconductor avalanche photodiode (APD) quality and reliability for high-speed communication applications. Samples from several manufacturing runs pre-screened through the standard production batch validation showed very low start of life low-frequency noise levels. The LFN test indicates the high quality of the devices with respect to noise characteristics. We also investigated the noise characteristics of production reject devices, some of which exhibit a 1/f type noise peak at the guard ring punch-through voltages, and an increase in noise intensity at punch-through voltages after long term accelerated lifetesting (>1000 h at 200°C and 100 μA). Useful information on device quality can thus be obtained from the noise measurement results performed in the deep breakdown bias range (27-30 V), where a sharp peak of the Lorentzian type noise may be observed. This feature is believed to be due to intensive recombination processes at defects in interlayer regions. It is also shown that avalanche photodiodes containing some defects exhibit not only increased dark current and low-frequency noise level, but also increased multiplication excess noise factor which decreases with increasing input light intensity. This work shows that LFN spectroscopy is very useful for the localization of noise sources, and provides important information for further product quality improvement.