In the present study, second law analysis is introduced for circular cylinder confined between parallel planes. An analytical approach is adopted to study the effects of blockage, Reynolds and Prandtl numbers on the entropy generation due to the laminar flow and heat transfer. Four different fluids are considered in the present analysis for comparison purposes. Heat transfer for the cylinder at an isothermal boundary condition is incorporated. In general, the entropy generation rate decreases as the blockage ratio decreases. In addition, the entropy generation rate increases with increasing Reynolds and Prandtl numbers. At a fixed Reynolds number, the effect of blockage becomes more noticeable for higher Prandtl number fluid. Similarly, for the same fluid, the effect of blockage becomes more noticeable as the Reynolds number increases.