The maximum recommended transport time for blood cultures is 4 h [L. S. Garcia (ed.), 2007 Update: Clinical Microbiology Procedures Handbook, 2nd ed., 2007]. In a previous study, we found that the average transport time was 10 h. In this cohort study, we measured transport times for blood cultures in a larger sample and identified predictors for transport times. A total of 4,322 blood cultures from 1,313 patients were included. The median transport time was 3.5 h, with 47% of cultures exceeding the recommended 4 h. Off-site location and type of clinical specialty were the most important predictors of long transport times. Cultures collected during weekend days or on wards at the largest distances from the laboratory were also associated with long transport times.