The present article summarizes the main results of the cross-sectional part of the 'Munich Vulnerability Study' in which healthy first-degree relatives of patients with an affective disorder were investigated by assessing their neuroendocrine, polysomnographic and psychometric status. As patients with an acute episode of a major depression, the group of the healthy relatives exhibited signs of a hyperactive hypothalamic-pituitary-adrenocortical system verified by the combined dexamethasone corticotropin-releasing hormone (DEX/CRH) test, as well as a slow wave sleep deficit in the first sleep cycle and an increased amount of rapid eye movements during REM sleep. The psychometric profile of the healthy relatives was characterised by elevated scores on the scales measuring 'Rigidity' and 'Autonomic Lability'. On a single-case level, 32% of the healthy first-degree relatives of patients with an affective disorder exhibited 'depression-like' features or conspicuous findings in at least two of the three (i.e. neuroendocrine, polysomnographic, psychometric) areas assessed. Whether the relatives with the neurobiological and psychometric abnormalities we identified have a higher risk for developing an affective disorder than those without has to be answered by the still ongoing prospective part of the study.