OBJECTIVES: This study was carried out to assess, from the viewpoint of cost-effectiveness, the optimum number of blood cultures for adults patients with infection in China. METHODS: A decision tree was conducted for a cohort of Chinese adults aged 18 and above with infection and simulated the effects of only one-time, two-time and three-time blood cultures. The detection rate and survival rate of complications were main outcomes and infectious endocarditis, meningitis, septic shock and kidney failure were considered as complications of infection in the model. The cost of blood culture, antibiotics and complications, the detection rate, incidence and survival rate of complications were collected from literature reviews. Sensitivity analyses were conducted to evaluate assumptions of the model and to identify which model inputs had most impact on the results. RESULTS: The detection rate and the survival rate of complications were calculated as 65 and 97.9% for one-time blood culture, 80 and 98.0% for two-time blood cultures and 96 and 98.2% for three blood cultures, respectively. When using detection rate as outcome and willing to pay is more than RMB500 yuan, two-time blood cultures were cost-effective. The cost of blood culture and the detection rate will affect the results. When using survival rate of complications as outcome, two-time blood cultures was cost-saving and better than one-time blood culture. CONCLUSIONS: This analysis suggests that a 2-time blood culture collection method is recommended for blood culture for patients aged 18 and over with infection from the aspects of cost-effectiveness and diagnostic accuracy in China.