A significant proportion of the population aged 75 and over experiences an episode of major depression. Symptoms of depression manifested by elderly patients are sometimes treated as a natural element of the aging process, leaving elderly patients undiagnosed or misdiagnosed. It is postulated that the use of the Mediterranean diet may counteract the development of depression and alleviate depressive symptoms due to the anti-inflammatory properties of this diet. The aim of the systematic review was to assess whether the degree of adherence to the Mediterranean diet is related to the occurrence and severity of depressive symptoms in people over 65 years of age. We included 9 studies out of 317 identified manuscripts. The results of the studies included in the review indicate that adherence to the principles of the Mediterranean diet by elderly people may bring beneficial results in the prevention of depressive symptoms and justify further search for the relationship between this diet and its individual components with the mental well-being of old patients.