Grain-growth kinetics of (Mg0.85Fe0.15)O ferropericlase was investigated at a temperature of 1873 K up to a pressure of 25 GPa under dry conditions using a Kawai-type multi-anvil apparatus. The grain-growth kinetics of ferropericlase is described by G(n) - G(0)(n) = k(0) exp(-E* +PV*/RT)t where G is the average grain-size at annealing time t; G(0), the initial average grain-size; P, pressure; R, the gas constant; and T, absolute temperature. Least squares fit of this equation for the present data and our previous data on the same material yielded n = 2.8 +/- 0.2, k(0) = 10(-8.4 +/- 1.1) m(2.8)/s, E* = 273 +/- 24 kJ/mol, and V* = 4.5 +/- 0.2 cm(3)/mol. The present results show that at the conditions at the top of the lower mantle (700 km depth), the grain-size of ferropericlase in a single phase system evolves to similar to 1 cm after significant geological time of 1 My. The present results may be applied to regions where single phase ferropericlase aggregates are present, say by deformation-induced phase segregation. In these areas, the grain-growth kinetics is fast so that one expects a large grain-size that will results in strong lattice-preferred orientation causing significant seismic anisotropy. Citation: Tsujino, N., and Y. Nishihara (2010), Effect of pressure on grain-growth kinetics of ferropericlase to lower mantle conditions, Geophys. Res. Lett., 37, L14304, doi: 10.1029/2010GL043491.