Protein-energy malnutrition (PEM) is a pathological condition arising from a lack of proteins and calories, most common in infants and young children. It manifests as marasmus, due to calorie deficiency, or kwashiorkor, due to protein deficiency. PEM is a global problem causing childhood mortality and morbidity. Causes include inadequate food intake, infections, and poor hygiene. Treatment involves stabilizing the patient, rebuilding tissues, and preparing for follow-up rehabilitation. Preventive measures encompass promoting breastfeeding, improving family diets, and early diagnosis and treatment of infections.