The Numbers of elderly people are gradually increasing in our society, and mood disorders are progressively increasing among older people. Old age depression may also occur after life events: the death of the significant other, economical reasons, health problems (neurological and/or cardiovascular diseases, arthritis, cancer, nutritional deficiency) and can develop into a depressive state. Old age depression is often mistreated, or undertreated, and also underdiagnosed, and this for several reasons: older people reduce their social relations, depression very often presents as a comorbidity with organic diseases (that cover and mask depressive symptoms); finally,the patient may believe that a depressive state is a normal course of life in older people. Recovering from depression is really feasible both in young/adults and in old people, but in older people we can find a higher frequency of admission to hospital, or mortality or suicidality. The depressive symptoms in old age depression is similar to those in adults, however the following aspects require special care, in order to ensure a correct diagnosis despite the presence of comorbidities: - the mood: in contrast with the young and adult, old people often do not complain about their low mood; - the psychotic simptoms: hypocondriacal and psychotic, including hallucinatory symptoms are often present; - the anxiety symptoms: these are often present together with neuro-sensory symptoms; - the somatic symptoms: the comorbidity with organic diseases can mask and overlap the depressive state; - reduction of congnitive functioning: in these cases, which are quite frequent, it is essential to make a differential diagnosis from "pseudodementia" and "dementia". In conclusion, several factors contribute to the onset of depression in old age, so that we can assert that it is a really a multifactorial disease.