Although silicon is not considered an essential element, but a lot of researchers mentioned that plant development, growth and yield have been increased by the application of Silicon to soil and or plant. Also it is known to reduce rice diseases. Experiments were conducted in 1999, 2000 and 2001 to study the effect of different sources of silicon on rice diseases ie. blast, brown spot and false smut in Egypt.  So, Silicon was applied to soil at the rate of 10 or 20 g./ m² and spray   2 or 4 g./ L. of Magnesium silicate (MgSi) were tried, silica gel 0.25 or 0.5 g/m², sodium metasilicate 20 g/m²  in soil. On the other hand burnt or unburnt rice husk or rice straw at the rate of 100 or 200 g/m², were used as silicon sources applied to soil. The conclusion from these experiments can be summarized as follows: MgSi as spray or soil application; burnt rice straw 200 g/m² and burnt rice husk 100 g/m² significantly decreased both leaf and panicle blast severity. For the brown spot disease, the severity of infection was significantly decreased with all silica sources in seasons 2000 and 2001. The most effective treatments were burnt rice husk at the rate of (100 g/ m²) in soil, burnt rice straw (200 g/m²) and MgSi (20g/m²) incorporated into soil and two sprays of MgSi at complete vegetative growth and one spray at booting stage. The most effective treatment in case of false smut disease was recognized by the application of MgSi sprayed twice during leaf stage and the third one at booting, in spite of the significant decrease due to the addition of other sources of silica on either percent or severity of false smut infection.  In addition, an experiment was conducted to study the effect of MgSi at the rate of 2 g/L as a sprayed with Beam individually or alternatively.  The results revealed that Beam and MgSi when sprayed at leaf, followed by MgSi at late booting, was the best treatment for both blast and brown spot.  While in case of false smut MgSi as foliar application at late booting gave the lowest infection in spite of the significant effect of the other treatments.