The present study is conducted to examine the entropy generation and second law analysis for the laminar flow passing through a circular duct with restriction and swirl. The governing fluid and energy equations are solved numerically for the combination of the conditions of restriction and swirling. The dimensionless quantities for the entropy generation, heat transfer and irreversibility are developed. The influence of Prandtl number, restriction and swirl on the dimensionless quantities and merit number are discussed. It is found that the irreversibility increases with increasing Prandtl number. The effect of swirling and restriction on the dimensionless quantities is more pronounced at high Prandtl numbers.