In this study, fluid flow and heat transfer in partially divided square enclosures are numerically investigated. It is assumed that, the horizontal end walls of enclosures are adiabatic or perfectly conducting and the left side wall and the right side wall of enclosures are maintained at uniform but different temperature. Temperature and velocity distributions in the enclosure for laminar and steady flow are determined by solving continuity, momentum and energy equations for appropriate boundary conditions. A computer program based on the control volume approach and SIMPLE algorithm is developed. A conjugate formulation at solid-fluid interface is used and thermal conductivity and viscosity are calculated using a harmonic mean formulation in order to handle abrubt changes in the material properties. By using the fact that, heat transfer from hot side wall by conduction must be equal to the heat transfer to the fluid by convection, the local Nusselt number is evaluated. The effect of Rayleigh numbers, number of partition and height of partition on fluid structure and fluid flow are investigated. It is observed that, mean Nusselt number increases with increasing Rayleigh number and decreases with increasing number of partition, however, decrease in mean Nusselt number is less at low Rayleigh numbers. Furthermore, increasing partition height, decreases mean Nusselt number.