Neonatal or infantile hypocalcemia is often manifested by convision, tetany, irritability, cyanosis, carpopedal spasm or laryngospasm. 40 Patients with neonatal and infantile hypocalcemia who were admitted to the pediatric department of Severance Hospital of Yonsei University Medical College over ten years(1969~1978) were reviewed clinically and the following results were obtained. 1) Male and female ratio was 1.9:1. 2) There were 9 prematures and 31 fullterms according to their gestational ages. 3) Age incidence was peaked in the groups of age from one day to three months, numbering 28 cases(75%). 4) In terms of perinatal histories there were toxemias of pregnancy(2 cases), C-sections respiratory distress syndromes(2 cases) in mothers side, and prematurity (9 cases) respiratory idstress syndromes(2 cases) and difficult deliverly(1 case) in infants?side. 5) The feeding methods were milk feedings in 25 cases, breast freedings in 10 cases and mixed feedings in 2 cases. 6) The clinical symptoms and signs of hypocalcemia were convulsions in 35 cases, irritability in 21 cases, cyanosis in 16 cases. Vomitings in 14 cases, lethargy in 7 cases?carpopedal spasms in 5 cases and laryngospasms in 4 cases. 7) Serum calcium levels were 6.4mg/dl(3.8~7.5mg/dl) in prematures and 6.3mg/dl(4.5~7.5mg/dl) in fullterms. 8) causes of hypcalcemia were considered as transient hypocalcemia in 29 cases, deficiency rickets in 4 cases, gastrointestinal diseases in 3 cases and unknown in the remaining 4 cases.