A direct numerical simulation of a moderate adverse pressure gradient turbulent boundary layer flow on a flat plate was performed on a fairly long domain with a Reynolds number from Re θ ∼ 2000 to Re θ ∼ 8000. The mean flow and Reynolds stress statistics are analysed. The mean streamwise velocity profile does not exhibit a clear log region even at the highest Reynolds number. The Reynolds stresses exhibit a well defined peak in the outer region which moves away from the wall before to stabilise near 0.45 boundary layer thickness. These outer peaks are the consequences of an excess of production over dissipation. The large scales structures analysed by means of two point correlations of streamwise fluctuating velocity are shown to be strongly modified by the adverse pressure gradient.