Comparing the results of exact quantum calculations and those obtained from the Einstein-Brillouin-Keller–like quantization scheme of Silvestrov et al. [Phys. Rev. Lett. 90, 116801 (2003)] we show that the spectrum of Andreev billiards of mixed phase space can basically be decomposed into a regular and an irregular part, similarly to normal billiards. We provide a numerical confirmation of the validity of this quantization scheme for individual eigenstates and discuss its accuracy.