Background: Polycythemia (PC), defined as packed cell volume (PCV) ≥65% is seen in many admitted neonates. Apart from PCV, other red blood cell (RBC) indices may also be affected in these neonates with PC. These RBC indices can have clinical implications and may determine whether the baby becomes symptomatic or not and also play a role in deciding the severity of symptoms. The indices may affect the outcomes of these babies. Therefore, we aimed to determine the impact of PC on other RBC parameters in neonates and analyse whether they differ from babies without PC. Methods: We studied 73 neonates admitted to the neonatal intensive care unit with PC for the RBC indices. These indices of infants with PC were compared with controls (1:1) who were admitted infants with matched characteristics and no PC. Results: 73.9% of the total study subjects with PC had hypoxic ischemic encephalopathy (HIE) and/or were small for gestational age. The red cell distribution width (RDW) and RBC count in polycythemic neonates were significantly higher than in neonates without PC. A significant positive linear correlation was found between PCV at admission and mean corpuscular hemoglobin concentration and RBC count. The mean corpuscular volume (MCV) significantly increased with the severity of PC. Conclusion Our study highlights that PC is associated with changes in other RBC parameters as well. The RBC count and RDW in neonates with PC were significantly different from controls and the MCV varied with the severity of PC. The RBC parameters in polycythemic neonates can be studied further for clinical implications in these neonates.