In this study, the effects of wheat-based diets processed in a hammer mill with different sieve diameters (4000 (fine), 5000 (medium) and 6000 (coarse) μm) and enzyme addition (0 and 300 g/ton) on the performance, slaughtering characteristics, tibia properties, jejunum morphology and pancreatic enzyme secretion in broilers (1-42 days) were tested in a 3×2 factorial design. A total of 480 one-day-old chickens were randomly distributed into 6 treatment groups of 5 replicates, each containing 16 birds. The performance of broilers was not affected by particle size. Dietary enzyme supplementation improved body weight on the 1-10th day period but did not affect other performance parameters. Thigh and abdominal fat increased with fine particle size, breast weight increased with medium particle size and gizzard weight increased with coarse particle size. Enzyme addition decreased the carcass and gizzard weights. Tibia breaking strength decreased with fine particle size. Tibia wall thickness and ash increased with enzyme addition. Pancreatic enzyme secretions increased in the coarse group and with enzyme supplementation. Jejunum histomorphology worsened with coarse particle size, while enzyme inclusion improved histomorphology. The interactions affected feed consumption (25-42nd day), feed conversion ratio (11-24th day), breast weight, tibia breaking strength and ash, pancreas weight, lipase activity and villus parameters. These findings demonstrated that coarse grinding of wheat-based diets improved bone development and pancreatic enzyme activity without affecting performance while worsening jejunum morphology. Enzyme addition positively affected bone and digestive system development.