Measurements of turbulent kinetic energy dissipation rate ε were conducted in selected regions in the Yellow, East China and East/Japan Seas using a microstructure profiler in the warm seasons of 2005 and 2006. The data show different vertical structures of ε with a wide range from 10-10 to close to 10-5 Wkg-1 between the three seas. The largest value of ε, 10-5 Wkg-1, appears in the surface layer. In the Yellow Sea and East China Sea, ε reaches 10-6 and 10-7 Wkg-1 near the bottom and in the lower thermocline, respectively, indicating direct effects of tidal stirring and internal waves on the generation of turbulence. Values of the vertical eddy diffusivity Kz estimated from ε and buoyancy frequency are O(10-3 m2s-1) but it exceeds 10-2 near the surface and the bottom in the Yellow Sea and East China Sea. In the East/Japan Sea, Kz is generally smaller than that in the Yellow Sea and East China Sea by an order of magnitude.