Adrenal abscess is an uncommon finding in neonates and young infants. It may have a fatal outcome if inadequately treated. This case report describes the successful diagnosis and treatment of a left-sided adrenal abscess in a 5-week-old girl. Abdominal US and antigranulocyte antibody-scintigraphy showed an encapsulated suprarenal mass with debris suspicious for an adrenal abscess. Treatment is generally surgical. In this case, however, we performed US-guided percutaneous drainage combined with intravenous antibiotic treatment. The child recovered fully.