The existence of endogenous benzodiazepines such as diazepam and nordiazepam has been provided in human blood and brains as well as in medicinal plants and foods. It must be stressed, however, that in plasma and brain tissue there are also other benzodiazepine-like compounds termed 'endozepines' which are not halogenated. A synthetic pathway for the production of benzodiazepine-like compounds and endozepines has not yet been found, hence it may be surmised that these compounds could be of exogenous source. Changes in the level of endogenous circulating benzodiazepines due to food or drug ingestion could be responsible for pathological conditions. Clinical experiments were designed in order to study the levels of the endogenous benzodiazepines in vegetables and in the blood of control subjects and of cirrhotic patients. These patients accumulate benzodiazepines because of decreased liver metabolization capacity and impaired renal secretion, reaching plasma concentrations similar to those recorded in commercial benzodiazepine consumers.