In order to account for the morphology observed in surface replicas of polyethylene spherulites, two possible mathematical models are proposed. These are based on the requirement that lamellae with a given twist angle about the radius vector of the lamella form continuous surfaces. It was found possible to arrange the lamellae in such a way that the locus of all points of given lamellar twist within the spherulite was a continuous surface of three‐dimensional spiral form. A computer was used to plot out the ring structure to be expected on sections through the models, and these were compared with the actual ring structures observed on surface replicas of polyethylene spherulites. On all sections not passing through the spherulite center, both models show a double‐armed spiral form in keeping with observed structures. Sections passing through the centers of the models do not always give double‐armed spirals, depending on the model.