Hypophosphatasia is the inborn error of metabolism that is characterized by low serum alkaline-phosphatase activity, due to loss-of-function mutations within the gene for tissuenonspecific isoenzyme of alkaline phosphatase [TNSALP]. The manifestations of hypophosphatasia range from neonatal death with almost no skeletal mineralization to dental problems in adults without any bone symptoms. There are no case reports of infantile hypophosphatasia in Israel. The existence of enzymatic replacement treatment for this disease makes it important to diagnose this problem as soon as possible. We describe a 5 month old infant who presented with bulging fontanel, neonatal pyridoxine responsive seizures, respiratory distress, hypercalcemia and very low blood levels of alkaline phosphatase. The baby was found to have a homozygote mutation in the TNSAP gene.