A possible method of pupil apodization using Zernike's phase contrastis presented. I recall the phase contrast principle and show through numericalsimulations that it may be used to generate an apodization using very simpleoptics in the monochromatic case. I also demonstrate that the generalformalism for Lyot and Roddier & Roddier coronagraphy can be extended to theZernike case. This may improve the quality of the simulations undertakento demonstrate the technique's performances.