A numerical analysis of laminar flow and heat transfer in a tube bank is described. The two-dimensional Navier-Stokes and energy equations are solved numerically for successive subregions from the inlet to the exit of the bank by a procedure catted the “one step forward and half step backward iteration method” and by using a hybrid grid system. Calculations are carried out for an in-line square tube bank up to five rows deep, with pitch-to-diameter ratios 1.5 × 1.5, under the conditions of uniform tube wall temperature, Re = 60, 120, and 300, and Pr = 0.7. Stream, isovorticity, and isothermal lines through the whole tube bank, local and average Nusselt numbers, pressure distributions along the tube walls and in the flow directions, and friction factor are presented. The friction factor and average Nusselt number agree well with published experimental results. An analogous relation between an in-line tube bank and parallel plates with respect to developing heat transfer characteristics is presented.