In the assessment of septic arthritis of the hip in a pediatric population, ultrasound is a safe and easily conducted method to confirm an effusion. The need for MRI to further evaluate the patient for adjacent infection before treatment is debatable. Once an effusion is confirmed on ultrasonography, we have found that septic arthritis of the hip does not need advanced imaging before arthrotomy and debridement. Patients who fail to clinically respond to an initial hip arthrotomy and appropriate antibiotics may benefit from an MRI for the identification of concomitant infections that may require surgical intervention.