Abstract: In an envelope edge slitter having a base, apparatus for feeding the envelopes one-by-one from the bottom of a stack at an input station to slitter blades in which an endless elastic belt extending around an eccentric pulley has an upper reach disposed in a slot n the base at the input station. The eccentricity of the pulley alternately brings the belt into and out of engagement with the lowermost envelope in the stack while the elasticity of the belt, the eccentricity of the pulley and the speed with which the belt is driven are such as to produce a whipping action of the upper reach of the belt which ensures that adjacent envelopes of the stack are separated and are fed one-by-one to the slitter blades.