The concept of codependency stems from the field of chemical dependency. Initially, codependent individuals meant women who dominated their partners and took care of them, while women actually were dependent upon their husbands. Nowadays, it has been recognized that men can become codependent as well, and its presence is not limited only to the relationship. This paper reviews the various interpretations of codependency and the empirical researches on the etiological factors of codependency. The explanatory models of codependency can be placed on a continuum of severity: psychopathology on the level of personality disorder, behavioural addiction, or excessive feminine behaviour. The etiology is mutifactorical: biological, psychological and social elements are also listed among etiology factors. The individual variability of the predisposition to care, failure of prefrontal cortex to inhibit empathic responses, a multitude of aversive experiences in a dysfunctional family (e.g. parental conflicts, emotional abuse, neglect and parentification), changes in the perception of women's role, and the emergence of substance abuse in the family could play a role in the development of codependency. Codependency is often unrecognized. Codependent individuals visit the health care system with stress-related or depressive symptoms which can mask the underlying causes, thus, it is possible that they will only receive symptomatic treatment. Through its trans-generational nature, codependency endangers children growing up in the family.