Although angiotensin II receptor blockers (ARBs) are contraindicated during pregnancy, new cases are currently being reported.A 32-week preterm neonate was admitted after C-section due to maternal oligohydramnios. He presented with Potter phenotype, pulmonary hypoplasia with pneumothorax, systemic hypotension and anuria. He required chest drain insertion and continuous positive airway pressure (CPAP), volume expansion plus inotropic support with persistent renal failure. Mother confirmed olmesartan intake during entire pregnancy. Peritoneal dialysis was started with improvement in renal markers and progressive recovery of renal function. He has been followed up until the age of 2 years, observing improved renal function with a glomerular filtration rate (GFR) of 58 mL/min/1.72 m2.Both angiogenesis-converting enzyme inhibitor and ARBs affect nephrogenesis; ARBs being more harmful due to its higher activity. Although some patients may recover normal renal function, its teratogen effect may have fatal consequences. Thus, it is important to emphasise its harmful effects in neonates to avoid new cases.