Fine silica particles surface-treated with a silane and having primary particles having a particle diameter of from 0.01 to 5 μm, which fine silica particles fulfill the following conditions (i) and (ii), a process for their production and an organic resin composition containing such particles as a component are provided. (i) When an organic compound which is liquid at room temperature and has a dielectric constant of from 1 to 40 F/m and fine silica particles are mixed in a weight ratio of 5:1 and shaked, the fine silica particles disperse uniformly in the organic compound, and (ii) the quantity of primary particles remaining as primary particles when methanol is evaporated under heating by means of an evaporator from a dispersion prepared by dispersing the fine silica particles in methanol and thereafter the particles are held at a temperature of 100° C. for 2 hours, is in a percentage of at least 20% based on the quantity of primary particles originally present. The present fine silica particles are highly dispersible and low aggregative, and the organic resin composition containing them is useful for obtaining films having a good transparency and superior blocking resistance, slip properties and scratch resistance.