Pain may be the cause of depression but it may develop also during depression. In the former case the development of depression can be influenced, apart from pain, by a number of other factors, such as personality features and pharmacological treatment. In the latter situation pain can be a manifestation of endogenous depression. The author describes the complex patterns of various forms calling particular attention to pain as their element which can be foremost in the clinical picture. The principles of recognition of masked depression are discussed.