Children with complaints of hip pain, a painful limp, or refusal to weight bear commonly present to the Emergency Department (ED). The ability to use point-of-care ultrasound in the ED to diagnose a hip joint effusion and to guide arthrocentesis can be helpful to facilitate diagnosis and management of these children. The capsular-synovial thickness of the hip is measured from the anterior bony cortical surface to the posterior surface of the iliopsoas muscle at the concavity of the femoral neck. A capsular-synovial thickness>5 mm, or >2 mm difference compared to the asymptomatic contralateral hip are the described sonographic criteria for hip joint effusion in children. We report on the use of point-of-care ultrasound to diagnose hip effusion and to guide arthrocentesis in a series of pediatric patients presenting with hip pain to the ED.