Tooth eruption comprises a highly coordinated cascade of complex cellular and molecular interactions resulting in axial movement of the tooth germ from an intra-osseous position to its functional occlusion. Odontogenesis is under genetic control, governed by more than 300 genes, with environmental factors playing a comparatively minor role. Delayed tooth eruption (DTE) describes the most frequently encountered deviation from normal eruption and can be the solitary materialization of local or systemic pathology. Where local pathology has been excluded, the dentist should be aware of the multitude of systemic conditions that may be contributing, and liaise with relevant medical colleagues. This article provides a review of the literature regarding the systemic causes of DTE. CPD/Clinical Relevance: Systemic conditions can be aetiological factors in delayed tooth eruption.