Abstract. Angiotensin converting enzyme inhibitors have been used in the neonatal population for both cardiac and renal diseases. Past reports have described deleterious renal and neurological consequences as a result of these drugs. This report describes two infants receiving enalapril for different indications who suffered renal impairments, likely a result of concomitant diuretic use. These cases demonstrate the risks associated with ACE inhibitor use and the importance of vigilant monitoring when using these medications.