Oral pigmentation may be physiological or pathological in nature. It may represent a localized anomaly of limited significance or the presentation of potentially life-threatening multisystem disease. Evaluation of a patient with oral pigmentation requires a systematic approach with resource to appropriate investigations in certain circumstances. A full history of evolution of the pigmentary changes, as well as inquiring into family history, drug ingestion and systemic symptoms of concurrent disease are clearly important in the assessment. The duration, pattern, hue and distribution of colour changes can provide useful diagnostic clues. Special attention is given to newly appearing lesions, or those that have changed significantly in appearance, and biopsy may be needed to validate the clinical impression. This review should enable the reader to increase their familiarity with the assessment of oral pigmentation, the common causes of oral pigmentary change and the rarer disorders of pigmentation seen in this area. The systemic diseases that may give rise to oral pigmentation are detailed and the early signs of oral melanoma are highlighted, as well as the drugs which may cause pigmentary changes in this area and the different pattern of pigmentation they may induce.