We have studied the relaxation of IIIA-VIA and IIB-VIA compounds AB (110) and AB (1010) surfaces with LEED, and found that the best agreement between theory and experiment occurs in such a sturcture, in which the B atoms are tilted outward and A atoms are tilted inward, with an angle of rotation ω, keeping the bond length at surface A-B unchanged, and the first atomic surfaces layer distances d1=0.610-0.810? [for IIIA-VA (110)] , 0.536-0.825?[for IIB-VIA (110)] and 0.633-1.060?[for IIB-VIA (1010)] and the second surfaces atomic layer distances d2 = 1.300-1.610?[for IIIA-VA(ll0)] , 1.430-1.700?[for IIB-VIA (110)] and 0.820-0.930?[for IIB-VIA (1010)] and third one d3 = 1.410-2.440?[for 1I1A-VA (110)], 2.020-2.250?[for IIB-VIA (110)] and 1.910-2.440?[for IIB-VIA (1010)] . For this structure the relaxation susceptibility a are: 0.24±0.02[for IIIA-VA (110)], 0.25±0.02 [for IIB-VIA (110)] and 0.33 ±0.03 [for IIB-VIA (1010)].