We present a rare case of septic arthritis of the elbow in a child caused by Pseudomonas aeruginosa infection. In our patient, the 15-day delay before drainage may have led to the osteomyelitis of the capitulum and resulted in some persistent radiographic abnormalities. Although our patient has no subjective symptoms 5 years postoperatively, he has a slightly abnormal range of motion and gross lateral instability. Children with elbow pain and/or swelling with fever should be carefully examined for septic arthritis. Pseudomonas aeruginosa should always be kept in mind in such cases to avoid any delay in effective treatment.