The current status and understanding of various degradation phenomena in III–V opto‐electronic devices, especially,
normalGaAs‐
and
normalInP‐normalbased
double‐heterostructure lasers and light emitting diodes, are reviewed. Three major degradation modes are focused as follows: rapid degradation due to recombination enhanced dislocation climb and glide, gradual degradation during operation over a long term, and accidental catastrophic degradation due to current surge. In each degradation mode, degraded regions are investigated structurally and/or compositionally. Based on these results, the degradation mechanisms are discussed and several methods for eliminating the degradation are also suggested.