Statistics for To study the effects of stratification and slip velocity on the flow of fluid of variable viscosity over a permeable bed, we divide the flow into two zones called zone 1 and zone 2. Zone 1 pertains to the flow called the free flow governed by the Navier-Stokes equations in the region between the impermeable upper plate and the porous bed.. Zone 2 pertains to the flow in the bed governed by the modified Darcy Law. Using the slip velocity boundary condition, velocity distributions in zones 1 and 2 are obtained and are matched at the interface. The boundary layer thickness just beneath the permeable interface and the friction factor are also obtained. © 1976 Indian Academy of Sciences.