Primary hyperoxaluria type one (PH1) is a rare inborn autosomal recessive monogenic metabolic disorder due to hepatic alanine-glyoxylate-aminotransferase deficiency which results in excessive synthesis and urinary excretion of oxalate, inducing renal stone formation and deposition of calcium oxalate stones throughout the entire body. We present the clinical consequences in a 7-month-old male infant diagnosed with PH1. The patient was diagnosed by renal biopsy, which showed acute tubular injury with diffuse calcium oxalate crystals. The results of genomic DNA of AGXT gene were examined; the gene of the patient was similar to his mother, but different from his father and a healthy control. Mutation analysis of AGXT in the patient revealed the mutation, c.814T>GA, which was considered to be a silent mutation. During 22 days of hospitalization, supplementary pyridoxine was administrated intravenously at 50 mg per day for 3 days, and then orally at 60 mg three times daily. Meanwhile the patient was treated with peritoneal dialysis and after 12 months of follow-up, he unfortunately died of refractory bacterial pneumonia.