Illness in old age is characterised by vague and atypical presenting features which are often missed and wrongly attributed to the ageing process. This is particularly true of endocrine disorders where hypothyroidism may mas­ querade as dementia, where electrolyte imbalance may cause lassitude, and where diabetes mellitus may produce a wide range of complications com­ monly associated with ageing. It is our intention that our book provide straightforward practical guidance in this difficult area by delineating the effects of ageing on endocrine function and the clinical consequences of these; and by describing in detail the wide range of presenting clinical fea­ tures of endocrine disease in the elderly. Physicians are also often baffled and misled by the effects of ageing and disease on laboratory tests used in the investigation of endocrine disease. Our book describes these changes in detail, and gives guidance on which tests are most appropriate. Ageing and disease also produce subtle changes in the response of patients to drugs and replacement, and this is also dis­ cussed in detail. Subjects included separately and in depth include thyroid disease, the clinical features and treatment of diabetes, postmenopausal changes, bone disease, fluid and electrolyte imbalance, energy imbalance, and drugs caus­ ing endocrine and metabolic disorders. These have been chosen because we consider that they present problems which are particularly relevant to the elderly. Many other issues are covered in general textbooks of endocrin­ ology and have been omitted.