Bone marrow aspiration and biopsy (BMAB) is a painful procedure, and the routinely used local infiltration anesthesia (LIA) with lidocaine is unable to provide pain relief during the most uncomfortable phases. The primary endpoint of the present randomized, patient-blinded trial was to evaluate the efficacy of an opioid and benzodiazepine combination plus LIA (sedoanalgesia) in patients undergoing BMAB for hematological malignancies. The secondary endpoint was the safety of the procedure in an outpatient setting. Ancillary assessments were anticipatory anxiety related to pain recall in the event of re-biopsy, and adequacy of bone tissue harvested. Patients were randomly assigned to one of 2 arms to receive either sedoanalgesic placebo plus LIA (standard group) or oral fentanyl citrate 200 μg plus oral midazolam 5 mg plus LIA (combo group) during BMAB. Pre-procedural anxiety and procedural pain were assessed according to the Numerical Rating Scale (NRS: 0-10), dividing the time of the procedure into five intervals (T0, T1, T2a, T2b and T3) and evaluating the degree of discomfort at each time (T) in both groups. One hundred and sixteen patients were eligible for the study. At T2b (time of biopsy) and T3 (time after biopsy), a significantly lower perception of pain was registered in the combo group. Moreover, there were no significant sedoanalgesia-related side-effects. Finally, histological specimens were higher in quality in the combo group. Sedoanalgesia was highly effective in reducing pain during biopsy, diminished anticipatory anxiety in patients undergoing re-biopsy and led to fewer non-diagnostic specimens being harvested.