The lumbar plexus block is an advanced regional anaesthesia technique providing unilateral anaesthesia and analgesia for hip, thigh, knee, and lower limb surgeries. The lumbar plexus, formed by the ventral rami of L1–L4, is located within the psoas major muscle, making this block technically challenging. The block targets key nerves, including the femoral, obturator, and lateral femoral cutaneous nerves, offering effective pain control while sparing the sciatic nerve. It is particularly useful in high-risk patients who may not tolerate central neuraxial blockade. The technique can be performed using landmark, nerve stimulation, or ultrasound-guided approaches (e.g., Shamrock technique). Complications include nerve trauma, retroperitoneal haematoma, epidural spread, and local anaesthetic systemic toxicity (LAST).