Some research groups have pointed out that the pressure-transport effect in the turbulenceenergy transport equation becomes important for some kind of complex turbulent flows. Recent direct numerical simulation by Yao et al. (Theore. Comput. Fluid Dynamics, 14 (2001), 337-358) showed that the effect of the pressure-diffusion process was significant in a recirculating flow. In this study, three eddy-viscosity models (EVMs) were tested for a separated flow behind a rectangular trailing edge with or without the pressure-diffusion model proposed by Suga (J. Fluids Engng., 126 (2004), 634-641) thereby its effect was investigated in detail. The computational results elucidated that the pressure-diffusion model gave a definite influence on the predictive performance of EVMs, in particular in the recovery region downstream of the separation bubble. Furthermore, detailed discussion of each term of the pressure-diffusion model strongly recommended the usage of a non-linear eddy-viscosity model.