This experiment was conducted to investigate the effects of different feed restriction methods and changing physical form of feed during different rearing phase on performance, uniformity, mortality, carcass characteristics and gastrointestinal alterations in male and female broilers. For this purpose, 1144 male and 1144 female day old broiler chickens were used in a completely randomized block design. Experimental treatments included: A) control (pellet feed from 0-42 days), B) mash feed from 0-42 days, C) 5% diluted pellet feed from 0-42 days, D) 5% diluted mash diets from 0-42 days, E) crumble feed from 0-10 and 5% diluted pellet from 11-42 days, F) mash feed from 0-10 days and 5% diluted mash from 11-42 days, G) Pellet diet with 4 hours feed restriction from 11 to 24 days, H) mash diet with 4 hours feed restriction from 11 to 24 days, I) Crumble diet from 0-10, Mash from11-24 and Pellet from 25-42, J) Crumble from 0 - 10 and mash diet from 11-42, K) Mash from 0-24 and Pellet diet from 25 - 42). productive performance were evaluated at the end of days 10,24 and 42. At days 24 and 42 of the rearing period one bird from each replicate was slaughtered in order to examine gastrointestinal alterations for different treatments. Body weight at the end of day 10 in the crumbled feed was significantly affected by nutrient density, briefly, the highest weight was obtained by consumption of diluted crumble feed (p 0.01). Feed form had a significant effect (p 0.01) on mortality while nutrient density had no significant effect on mortality in starter period; when the diet was standard, mash feed reduced mortality in comparison with crumble feed.In growing period four hours feed removal after four hours of darkness in both physical forms of feed did not affect feed consumption in both sexes. Furthermore feed restriction during the growing period caused more feed consumption in the finisher period, especially in the pellet diet. Changing feed form from pellets in starter period to mash in growing period, led to a significant reduction in feed intake compared to control diet (p 0.01). Changing feed, from pellet to mash, from ten days of age to the end of rearing period in females, led to lower feed intake and weight gain (p 0.01). Feeding mash diets compared to pellets, and diluted diets compared to standard led to increase gizzard weight. Diluted pellet diet also resulted in the lower relative weight of the duodenum. Feeding birds with low-density nutrients diet, resulted in lower height of villi in the jejunal region in both sexes (p 0.01). In addition, in both sexes, time limitation for feed consumption had a great contribution in development of villi’s length, as well as consumption of pellet resulted in the wider villi compared to mash feed (p 0.01). In conclusion, according to the final weight of broiler chickens, feeding broilers with lower nutrient density in mash feed can lead to lower performance, while feeding low-density diets in pellet form resulted in the same growth performance compared to the control. Keywords: Broiler, Feed restriction, Feed form, Dilution, Histomorphology