Abstract: In the context of sustainable construction practices, the utilization of industrial by-products like fly ash in brick manufacturing is gaining popularity. This study aims to evaluate the mechanical properties of fly ash bricks, such as compressive strength, water absorption, flexural (rupture) strength, density, and efflorescence, and compares them to traditional burnt clay bricks commonly used in Pakistan. Experimental results show that fly ash bricks exhibit higher compressive and rupture strength and lower water absorption compared to conventional clay bricks. However, moderate levels of efflorescence in fly ash bricks suggest room for improvement in certain applications. The percent difference between fly ash and clay bricks has been calculated to quantify their suitability for masonry construction in Pakistan. This research contributes to the understanding of how fly ash bricks could serve as an alternative in construction materials with a lower environmental footprint.