Silica distribution in rice husk was examined by scanning electron microscopy. Silica appeared as a solid structure in the outer epidermis and as a dispersed system inside the husk. Pretreatments (steam autoclaving, water autoclaving, alkaline leaching, gamma irradiation, and ultra sound) were applied in order to achieve an improvement in rice husk digestibility. Alkaline leaching removed a significant part of the silica structure, therefore allowing a larger area of exposure of the cell wall polymers to the degrading enzymes. Among the pretreatments, alkaline leaching appeared to be the most useful, while others seemed not to be very successful in attaining the desired effect.