The Authors present the description of surgical technique employed to restore the Functional balance of the 1st mctatarsophalangeal joint in hallux valsus, a technique introduced by Pisani in 1982. The theory is that the technique can: 1) correct the spacing of the big toe; 2) leave the surface of articular cartilages intact; 3) balance the muscular function by dissecting the phalangeal head of the abductor hallucis which is returned to the normal position and sutured to a capsular flap to create a dynamic pull; 4) respect the muscular insertions on the base of the first hallux joint so as to maintain flexor power; 5) facilitate reoperation in the case of recurrences. The main features of the technique are the following: 1) long dorsomedial incision to expose the first metatarsophalangeal joint; 2) mobilisation of the adductor tendon; 3) the dorsomedial and dorsolateral vessels and nerves of the big toe are left intact; 4» ample lateral capsulotomy, lysis of the lateral sesamoid, dissection of the phalangeal head of the abductor hallucis; 5) reduction of the head of the 1st metatarsal to its normal glenosesamoid position; 6) mediocapsular surgery and anchorage of the adductor tendon. The indications for this type of surgical treatment are also specified.