Maximally supersymmetric Yang-Mills theories have several remarkable properties among which cancellation of UV divergences, factorization of higher loop corrections and possible integrability. Much attention has been attracted to N=4 D=4 SYM theory. N=(1,1) D=6 SYM theory possesses similar properties but is non-renomalizable and serves as a toy model for supergravity. We consider the scattering amplitudes (2->n) and analyze their perturbative expansion within the spin-helicity and superspace formalism. The integrands of resulting diagrams coincide with those of the N=4 D=4 SYM and obey the dual conformal invariance. Contrary to 4 dimensions no IR divergences on mass shell appear. We calculate analytically 1 and 2 loop master integrals and extract the leading logarithmic asymptotics in all loops. Summation of the leading double logarithms leads to Regge trajectory which is calculated exactly. Summation of the leading powers and leading UV divergences results in brave assumptions concerning the behavior of the whole perturbation series. This leads us to a radical point of view on non-renormalizable theories. The first part of the talk follows the recent paper by L.Bork, D.Kazakov and D.Vlasenko arXiv: 1308.0117