Both posterior and anterior surgery have potential for complete scoliosis correction. Significant difference in judging the procedures still persists. Aim. To establish objective advantages and risks of the procedures, basing upon long term results. Method. From 1982–2007, 859 anterior(A) and 388 posterior(P) instrumentations were performed by the same surgeon. Single level thoracotomy used even in double curves. Spinal canal was never opened, rib heads left intact, ribs were fractured at the top of rib hump. Zielke rod was used for correction, and another rod added for aditional correction and stabilisation. Various posterior instrumentations were used. Results. CORRECTION (A)frontal 67-45-16(76%), sagital +6, (P)frontal 66-44-29(56%), sag+3; OP. TIME (A)140(50–300), (P)155(110–350); BLOOD REPL. (A)18%, (P)92%; HOSP STAY (A)10, (P)13; VC (A)-10%, (P)0%; SPORT ACT. (A)3mths, (P)12mths; MAJOR COMPLICATIONS: no deaths, (A)1 aorta rupture, 1 bronchus penetration, 0,7% haematothorax, 0,6% reinstrumentation, 0,7% infections demanding op, (P)2 paraplegia (0,5%), 3.9% infections, 4.9% reinstrumentation. Discussion. (A)required no neuromonitoring, no intensive care unit. Blood replacement was occasionally used only for double curves (11 segm), and in preop. anemia. Most of the complications were preventable. Hospitalisation was longer in (P) group due to wound problems. Pulmonary decrease was found only in curves greater than 100 °. Halo traction improved VC, but both instr. had no influence on further improv. In (A)VC recovered in 6 months. Conclusions. (A) can be performed in less radical and agressive way. Anterior release significantly mobilizes the spine and decreases necessary corrective forces. Infection was more frequent in (P) but consequences were more dramatic in (A). All major complications in (A) were preventable. There is temporary decrease in pulmonary function after (A). We could not find objectives for (A) to have more morbidity than (P). Due to superior results we still prefer (A) in surgery of AIS. Our indications for (P) is VC<40%, age, poor bone quality, surgery in upper thoracic spine