Corticosteroid therapy is widely used in the acute and chronic treatment of different diseases, with consequent possible onset of typical side effects on multiple systems of the organism, including also energy metabolism and metabolism of water and minerals (sodium, potassium, calcium and phosphorus). Clinical signs, related to the type and dosage of the steroidal drug, may lead to secondary illnesses with variable degrees of severity, depending on proneness of the individual patient and on the underlying disease that motivated the treatment. The role of dietetic intervention in the management of a patient chronically receiving corticosteroid therapy is not ancillary, although often underestimated, its aim being the reduction of some long-term therapy related side effects, and the correction of major metabolic derangements. In particular, the diet shall be moderately rich in protein (1.5 g/Kg/day of proteins) and low in fat (< 30% of calories, obtained mostly from unsaturated fatty acids), based mainly on complex carbohydrates (80%), providing 50% of the caloric intake. Diet has to be specifically characterized by food containing little sodium and yielding high amounts of water, calcium, magnesium and potassium. Minor directions concern the reduced intake of ethanol and purines. The efficacy of supplementation with antioxidant vitamins (vitamin C and E) and selenium is currently under investigation.