We present a case series describing a novel approach to the lumbar plexus, which we have named the psoas sheath block. In this technique, we deposited local anaesthetic into the potential space between the psoas major muscle and its surrounding fascia, in a manner similar to the rectus sheath block. We hypothesised this anatomical plane would facilitate the spread of local anaesthetic to the branches of the lumbar plexus, specifically the femoral, obturator and lateral femoral cutaneous nerves, as they traverse the body of the psoas major muscle on their course to innervate the hip and anterior thigh. In this report, we outline the technique and describe its application in six consecutive patients undergoing hip surgery.