The A beta 1-42 monomer structure was assessed with a 790 ns molecular dynamics (MD) simulation, and the results were compared with the NMR experiment on A beta 10-35 and A beta 1-40. Previous theoretical work in a model of the His13-His14 region of A beta defined the possible Cu(II) binding geometries at this site (Raffa et al. J. Biol. Inorg. Chem. 2005, 10, 887-902). MD simulations totalling almost 2 mu s were also carried out on Cu(II)/A beta 1-42 systems, using the ab initio structures as templates for the copper binding site. This work finds that the copper-free A beta 1-42 system may stabilize after similar to 350 ns into a collapsed coil conformation, and we find good agreement with some, but not all, of the structural features determined experimentally for the A beta 10-35 and A beta 1-40 peptides. The results of the Cu(II)/A beta 1-42 systems are compared to the Cu(II)-free A beta 1-42 simulation.