Abstract : Group B Streptococcus (GBS) infection is one of the leading causes of morbidity and mortality in the neonatal period in the USA. The centers for Disease Control and Prevention (CDC) issued a recommendation to prevent early-onset GBS infection in 1996 and a revised recommendation in 2002. Objectives : To perform a health economic analysis of the CDC recommendation using clinical data currently available in Thailand. Study design : Health economic analysis. Materials and Methods : After reviewing the literature regarding clinical data in Thailand, a decision analysis was performed to evaluate the outcomes of 3 strategies : universal culture screening, intrapartum risk factors assessment, and no prevention. Outcomes : The medical care cost for each strategy and incremental medical care cost for the prevention of one GBS case were analyzed. Results : Under the present conditions in Thailand and using the cost estimated from Siriraj Hospital’s charge in the year 2005, the no prevention practice was the most cost-effective strategy. The incremental medical care cost to prevent one GBS care for the universal culture screening and the intrapartum risk assessment were 594,754.17 Baht and 83,677.78 Baht, respectively. Conclusion : Although neither of the preventive strategies recommended by the CDC was cost-effective in general clinical practice in the present situation in Thailand, the intrapartum risk assessment strategy may be reasonable because the incremental cost to prevent one GBS case was less than 100,000 Baht.