I will discuss scattering amplitudes in N=2,4,8 SYM in three-dimensions, concentrating on the N=8 case, with an emphasis on which properties of the N=4, D=4 SYM amplitudes survive under dimensional reduction. The on-shell supersymmetry algebra makes the SO(N) symmetry of the amplitudes manifest, while the Lagrangian displays only manifest SO(N-1) symmetry. I will also discuss the possibility of non-local Yangian-type symmetry, connections to BLG, and some perspectives on loop level results. Based on 1103.0786 / 1109.2792.