Neonatal Hyperbilirubinemia is increasing in frequency and there have been suggestions that this may be due to some change in factors involved in delivery. In this study, among numerous hypothesized factors, maternal age, gestational age, birth weight, birth order, and methods of delivery were tested if there were statistical associations between these factors and occurance of neonatal hyperbilirubinemia. For the study 83 cases(jaundiced infants) and sex matched 332 controls (normal infants) were chosen from the hospital records in St. Mary's Hospital, Catholic Medical Center. For testing the association between hypothesized factors and neonatal hyperbilirubinemia, X2-test was applied and relative risk estimates(odds ratio) were calculated for judging the degree of association. Mantel-Haenszel method was also used for calculation of summary relative risk. Study results showed that there was a strong statistical evidence of association between neonatal hyperbilirubinema and instrumental delivery such as vaccum delivery. Birth order seemed to be associated with the neonatal hyperbilirubinemia in simple X2-test of univariate situation, but the association disappeared when the method of delivery was controolled. Other factors (maternal age, birth weight, and gestational age) revealed no influence on the occurrence of the jaundice even in the simple X2-test. This study was able to suggest that the incidence of the neonatal jaundice could be reduced by applying more skilled technique when instrumental deliveries were needed and by making more conservative decision about the use of instrumental deliveries.