Purpose <p>Blood cultures (BC) are the gold standard for diagnosing bloodstream infections, yet their diagnostic yield is low, leading to misdiagnoses and increased mortality among hospitalized patients. Previous studies have shown mixed results regarding the role of body temperature in predicting BC positivity. We aimed to explore the relationship between body temperature parameters and BC positivity in hospitalized patients.</p> Methods <p>A retrospective cohort study was conducted using data from a 5000-bed tertiary hospital between June 2022 and September 2025. The nearest temperature before BC collection and temperature fluctuation over the previous 24&#xa0;h were analyzed in relation to BC results via multivariate logistic regression adjusted for potential confounders identified through directed acyclic graph, and inverse probability of treatment weighting.</p> Results <p>The study included 4,481 episodes of BC collection corresponding to 2796 patients, with 1,281 positive and 3,200 negative results. A U-shaped relationship was observed between both body temperature parameters and BC positivity. Subgroup analyses showed significant interactions between body temperature parameters and antibiotic exposure, and infection sources in relation to BC positivity.</p> Conclusion <p>Body temperature parameters, particularly extremes and minimal fluctuations, are associated with blood culture positivity. These findings emphasize the importance of considering body temperature trends alongside other clinical factors such as immunosuppression, infection site, and prior treatment with antibiotics or antipyretics when considering BC collection.</p>