The transient hydrodynamics and thermal behaviours of the free convection from a vertical plate inserted in a semi-infinite domain partly filled with porous material are investigated. The role of the local macroscopic inertial term in the porous domain momentum equation is studied. It is found that the effect of the local inertial term on the domain behaviour is insignificant when Da < 1 x 10(-5) for all operating conditions. Also, the effect of the macroscopic inertial term is insignificant at large values of mu(R), where mu(R) > 2: 0, and over the entire ranges of alpha(R), K-R and Pr ( thermal diffusivity ratios, thermal conductivity ratios and Prandt1 number, respectively).