Septic arthritis of the hip is an acute infection, predominantly of bacterial etiology. Although Staphylococcus aureus is the primary pathogen in any age group, other potentially pathogenic microorganisms exist. We describe the case of an 18-month patient with septic arthritis of the hip with a rare causal agent (Haemophilus influenzae type F) and a good outcome. This case highlights the importance of considering other less common etiologic agents for septic arthritis in children, performing arthrocentesis with synovial fluid culture before starting antibiotic treatment, whenever this is possible. In addition, as in this case, it should be noted that a positive synovial fluid culture for Haemophilus influenzae forces typification of the bacteria in order to rule out or confirm a vaccine failure.