The present invention provides apparatus and methods for injection moulding polymeric articles. The method includes injecting pressurised liquid polymer into a mould cavity, the cavity incorporating a core pin and a pressure distribution means. Preferably the article is a cannula. The invention provides a mould for injection moulding articles from polymeric materials, the mould comprising at least two parts defining a cavity having a conduit portion incorporating a needle portion a channel for liquid polymer ingress a channel for pressurised fluid ingress a core pin for defining the conduit of a cannula, and a pressure distribution means for controlling the distribution of the pressurised liquid polymer. The end surface of the pressure distribution means defines the tip geometry of the cannula. The mould may incorporate a plurality of cavities. The method includes moving the pressure distribution means in a controlled manner to define the conduit of the cannula.
