A method and associated apparatus for gas assisted injection molding wherein a quantity of fluid molding material is injected through a first injection flow path in a gas assisted injection molding nozzle into a mold cavity. The injection is then stopped by interrupting the flow of fluid through the first mold cavity, and introducing a time delay if desired. After any time delay, a quantity of pressurized gas or fluid at a first desired pressure is injected into the mold cavity through a second injection flow path which is isolated from the first injection flow path. The pressure is then reduced to a desired holding pressure, and the pressure is held in the mold while the part cools enough to be self supporting, at which time the pressure is vented from the mold cavity, and the part removed. The apparatus used, by isolating the molding material from the gas passages, is able to be of a simpler construction, avoid clogging of the passages, and use larger gas passages, all without the use of any check valves.