Abstract: A process and apparatus for plastics injection moulding comprises injecting a quantity of molten plastics material into a mould cavity (30) and injecting pressurised gas (52) or pressurised liquid into the plastics material in the mould cavity. After holding the pressure of the gas or liquid on the plastics material in the mould cavity for a period of time in order to apply a packing pressure to the plastics material, a portion of the molten plastics material is expelled into one or more secondary cavities (32) or expelled back into the barrel (22) of the injection moulding machine. The step of injecting the plastics material may be effected with or without packing of the plastics material prior to the injection of the pressurised gas or liquid.