The Ostwald-ripening of tungsten grains in liquid nickel-tungsten matrix at 1540℃ was observed and the results are compared to the LSW (Lifshitz., Slyozov, Wagner) theory and Ardell`s theory. The specimen compositions were 99W-1Ni, 93W-7Ni, and 70W-30Ni by weight percent. The specimens were prepared by usual powder metallurgy techniques using tungsten and nickel powders of 2.6μ and 4.6μ average size, respectively. The sintering was carried out at 1540℃ in hydrogen atmosphere for times ranging from 10 minutes to 15 hours. The measured linear intercept distribution of the tungsten grains was compared to the theoretical values for diffusion contralled and interface reaction controlled mechanisms obtained by Exner and Lukas from the LSW theory. In the specimens of 93W-7Ni composition the linear intercept distribution is wider than those suggested by LSW theory during the initial period of sintering. However, as the sintering time becomes longer it approaches the equilibrium distribution corresponding to the reaction controlled mechanism for the particle growth, and after 15 hours of sintering the observed distribution resembles the reaction controlled case. In the 93W-7Ni specimens the average tungsten grain size γ￣increases with time ｔas γ￣ｔ⅓ predicted by the LSW theory for the diffusion controlled mechanism. However, since the measurements were made up to 15 hours of sintering before reaching the equilibrium distribution it is not possible to conclude definitely that the observed growth rate corresponds to the dissusion controlled mechanism rather than the reaction controlled mechanism. On the other hand previous experimental results on tungsten heavy alloys show tungsten particle growth rates following the diffusion controlled mechanism. Further indication for diffusion controlled growth is provided by the variation of the growth rate with the relative amount of grains and the matrix as shown by previous measurements on heavy alloys and indicated in the present investigation. It thus appears that the observed growth rates correspond to the diffusion controlled mechanism while the grain size distribution at equilibrium resembles the prediction of reaction controlled mechanism. This apparent discrepancy is resolved by Ardell`s recent theoretical result that when the amount of the matrix phase is small and the reaction rate is controlled by diffusion the average particle size follows the ｔ⅓ law as predicted by LSW theory but the distribution closely resembles the reaction controlled case in LSW theory. Thus the results of the present investigation agree in general with the predictions of Ardell`s theory.