Transforaminal epidural injection is an effective method for treating spinal pain but can cause devastating complications that result from accidental vascular uptake of the injectate or a direct vascular injury. We prospectively evaluated the patient factors that might be associated with intravascular uptake during transforaminal epidural injections. A total of 2145 injections were performed on 1088 patients under contrast-enhanced real-time fluoroscopic guidance. The collected data included the patient's age, sex, body mass index, diagnosis, injection level, side of injection, history of spinal surgery at the targeted level, and the number of injections at the targeted site. The overall incidence of intravascular injection was 10.5% (224/2145). The highest incidence was at the cervical level (28/136; 20.6%), followed by the sacral level (111/673; 16.5%), the thoracic level (23/280; 8.2%) and the lumbar level (64/1056; 6.1%). The difference was significant for the cervical and sacral level compared with the lumbar and thoracic levels (p < 0.001). Intravascular injection was not associated with the other patient characteristics studied.