Introduction. ACTH (adrenocorticotropic hormone) is a key regulator of adrenal production involving cortisol as an essential hormone for life. The melanin is a pigment which is produced by melanocytes at the level of melanosomes (the melanogenesis). Both MSH and ACTH are generated by the cleavage of POMC (proopiomelanocortin) after CRF (corticotropin-releasing factor) stimulation and then MSH acts on the skin causing hyperpigmentation. Aim. To introduce clinical data of literature that link hyperpigmentation with ACTH excess. Three main topics are introduced: Addison’s disease, ectopic Cushing’s syndrome, and Nelson’s syndrome. Method. This is a short overview of literature including papers that have been mostly published within last 5 years. General data. Hyperpigmentation in relationship to ACTH includes its high levels in addition to low cortisol in Addison’s disease and Nelson’s syndrome and high non-suppressible cortisol in ectopic Cushing’s disease. ACTH has a pituitary origin in first two situations and malignancy in the third one. A pituitary tumour is found in cases with Nelson’s syndrome. An autoimmune background may be associated with Addison’s disease. An iatrogenic component is brought by Nelson’s syndrome. All three situations are severe and life threatening of different scenarios. Conclusion. Hyperpigmentation may be the clue to connect dermatology to endocrine pathologies and ACTH massive release by a pituitary or a non-pituitary origin involves a complex panel of conditions.