The purpose of the passive leg raise test, also called the PLR test, is to assess cardiac volume responsiveness by elevating the patient’s bilateral lower extremities, which can enable blood return to the heart from both lower extremities, increasing cardiac preload. This is done by tilting the bed, keeping the patient’s torso in a 45° semi-recumbent position on a tilted bed, and then keeping the hips flexed at 45°, with the aim of increasing subsequent volume transfer. This test is an emerging method for accurate assessment of fluid management, with high sensitivity and specificity for volume responsiveness prediction and ease of administration and reliable results, and is an effective alternative to rapid rehydration tests and is the method of choice for emergency circulatory failure or hypotension. It is mainly used in patients with high clinical suspicion of hypovolemic shock, such as patients with severe trauma with excessive blood loss, and postoperative patients with early resuscitation of sepsis or admission to the ICU. The test should be performed with concomitant application of sympathetic tone enhancing or vasoactive drugs and should be followed up with timely, effective and rational rehydration therapy.