INTRODUCTION: Rapid and accurate laboratory diagnosis is essential for the effective treatment of bloodstream infection (BSI). AREAS COVERED: This review aims to address novel and traditional approaches that exhibit different performance characteristics in the diagnosis of BSI. In particular, the authors will discuss the pros and cons of the blood culture-based phenotypic methods, nucleic acid-targeted molecular methods, and host response-targeted biomarker detection in the diagnosis of BSI. EXPERT OPINION: This manuscript summarizes etiologic and host-based techniques in the diagnosis of BSI. Both methods are not mutually exclusive but should be selected based on clinical needs and laboratory conditions to help diagnose BSI more quickly and accurately.