Rapid degradation is a severe problem for the new blue-green laser diodes, even leading to speculation that the cause may be a fundamentally unstable lattice. Recent work has shown, however, that the mechanisms of degradation appear to be similar to those seen in GaAlAs systems. Twelve reasons, encompassing electronic, mechanical, thermodynamic and chemical parameters, are given that demonstrate the ruggedness of II-VI materials. Factors that could lead to enhanced degradation are also discussed. Several reasons for the rapid degradation of these diodes are postulated: strain, recombination- enhanced diffusion and phase instability. Approaches to improvements in lifetime, such as using material with hexagonal crystal structure and magnesium doping, are suggested.