Cytopenias are common among neonates in neonatal intensive care units (NICU). Although, bone marrow aspirations (BMA) are often performed as part of diagnostic work up but trephine marrow biopsies (BMB) have not been reported from living neonates. BMB is indispensable to accurately assess the cellularity and architecture. There is paucity of literature regarding the technique of BMB in neonates. In this report, for the first time, we describe trephine BMB from Posterior superior iliac crest (PSIC) using 18 guage BMA needle in six living neonates admitted to NICU where bone marrow biopsy findings helped in understanding the underlying mechanism and diagnosis of cytopenias.