In the beginning of 1960s, initial reports appeared pointing to a possibility of preventing depressive and manic recurrences in affective illness by means of long-term administration of lithium salts. Subsequent several years of controlled studies confirmed such prophylactic effect of lithium in affective illness beyond any doubt. Some patients in whom lithium administration was started in the beginning of 1970s may, by now, have received lithium for more than twenty years. The patient reported in the present paper, had began lithium treatment on April 1, 1971, after her third depressive episode since 1965. During 25 years of uninterrupted lithium carbonate administration in daily dose 1000 mg (for 5 years-750 mg) and with mean serum lithium concentration 0.6 mmol/l, the recurrences have not been observed, mental status was normal and professional (physician-ophthalmologist) and family functioning was good. Either somatic or mental side-effects have not occurred. Twenty five years of the patient's lithium treatment, was paralleled by important events for lithium therapy such as, i.a., autobiographies of prominent persons receiving lithium for porphylactic purposes, definition of a new category of psychotropic drugs (normothymic) with lithium as a prototype, establishing some mechanism of lithium action on intracellular transmission, discovery of antiviral and immunomodulatory effect of lithium as well as finding of decreased mortality of patients receiving long-term lithium therapy.