Propionic Acidemia (PA) is a rare metabolic disorder caused by the defect in enzyme (propionyl-coenzyme A (CoA) carboxylase) leading to the abnormal accumulation of metabolites of branched-chain amino acid catabolism in blood and urine. We describe the first ever diagnosed case in our setup of early onset PA in a 06 months old baby girl who presented with the complaints of decreased feed intake, lethargy, vomiting, failure to thrive, and intermittent seizures. The basic laboratory investigations showed pancytopenia along with high anion gap metabolic acidosis, urine dipstick positive for ketones, and hyperammonemia. Plasma amino acid analysis by ion exchange chromatography (IEC) showed elevated plasma glycine and lysine levels. Finally, urine organic acid analysis by gas chromatography-mass spectrometry (GCMS) showed marked elevation of 3-hydroxy propionate, methyl citrate, and 3-hydroxy, 2 methylbutyric acid with moderate rise in 3-hydroxy butyric acid without an elevation of methylmalonate in urine, thus giving the diagnosis of PA. Key Words: Propionic acidemia, Propionyl-CoA Carboxylase deficiency, Gas chromatography-mass spectrometry.