The immune system of children with acute lymphoblastic leukemia (ALL) is affected by both the underlying disease and the chemotherapy. Children with ALL receive sedation for diagnostic and therapeutic procedures, which may contribute to immune competence alteration. The effects of propofol-ketamine combination on the immune system of children with ALL have not been investigated. This cohort study was designed to assess the immunomodulatory activity of the propofol-ketamine combination on proinflammatory and anti-inflammatory cytokines of children with ALL undergoing painful procedures. We enrolled 20 children with ALL undergoing bone marrow aspiration (BMA) and lumbar puncture with methotrexate. All children received sedation with IV ketamine (0.5 mg/kg) and propofol (3±2 mg/kg). Plasma concentration of cytokines interleukin (IL)-1β, IL-2, IL-6, IL-10, IL-8, IL-12p70, and interferon-γ before sedation for BMA was represented as T0, during lumbar puncture with methotrexate sedation 6 hours after T0 was represented as T1, and 24 hours after BMA was represented as T2. Sedation with propofol-ketamine combination did not modify the plasma concentration of the most measured cytokines and the T helper 1/2 ratio in children with ALL. There was a significant reduction in IL-8 concentration 24 hours after BMA associated with the concomitant administration of steroids and methotrexate. These data suggest that sedation with propofol-ketamine combination may not affect the immediate outcome of children with ALL.