We describe the case of a previously healthy six-year-old boy with a right renal abscess due to a methicillin-resistant Staphylococcus aureus, which necessitated a radical nephrectomy. Although renal ultrasonography is often the initial tool to identify fluid collection, in our case the diagnosis was obtained only after performing an abdominal CT with intravenous contrast. It is therefore necessary to combine these different imaging techniques in all children with fever and abdominal/lumbar pain without any apparent cause in order to obtain an early diagnosis and minimise organ damage.