Psoas abscess associated with septic arthritis of the hip is unusual in infants. A 12-month-old infant presented with the complaints of fever, left hip pain and limp. Magnetic resonance imaging revealed left psoas abscess accompanied by septic arthritis of the hip. In this report, we present a case of psoas abscess with hip septic arthritis in an infant, and we describe the clinical and radiological findings and treatment of this case.