Objective: The aim of the study was to evaluate reliability, efficiency and side effects of two different combinations that are ketamine-propofol and fentanyl-propofol, in pediatric hematology patients undergoing lumbar puncture (LP). Methods: A total of 100 paediatric cases, aged 4-14 years, who were planned to undergo LP procedure were administered two different sedo-analgesia protocols. An anesthetist administered ketamine 1 mg/kg intravascularly (iv) to the ketamine group (K), then after 1 min 2 mg/kg propofol was administered iv. In the fentanyl group (F), 1 mcg/kg fentanyl was given and after 1 min 2 mg/kg propofol was administered iv. All patients were monitorized and the heart rate, blood pressure, oxygen saturation, number of LP attempts, the side effects and also additional doses and the physician satisfaction were recorded. Results: The requirement for additional doses was higher in Group F (p<0.001) and the physician satisfaction was lower in Group F (p=0.021). When hemodynamic parameters were compared, the reduction in F group was determined as greater than that in K group (p<0.01) Conclusions: Safe and effective sedation has been obtained with both protocols during LP. However, the ketamine propofol combination had a lower requirement for additional doses and the physician satisfaction level was higher.