This study was conducted to assess the effects of feed particle size (FPZ) AND crumble size (CZ) of STARTER DIET on growth performance parameters, carcass characteristics, AND small intestinal histomorphology in broiler chicks. Three hundred AND sixty male Ross 308 chicks were rANDomly distributed in a completely rANDomized design with 3 2 factorial arrangement consist of three screened FPZs (500, 1000 AND 1500 μ m) AND two CZs (1. 5 AND 2. 5 mm). Each treatment included six replicates (10 broiler chicks per cage) AND chicks were reared in the cage from 0-10 d of age. The results indicate that neither main factors nor interac-tion between FPZ AND CZ had any significant effect on body weight (BW) AND European production effi-ciency factor (EPEF) at 10 d. However, a significant interaction effect (P<0. 05) between FPZ AND CZ were observed for feed intake (FI), feed conversion ratio (FCR) AND feed efficiency (FE). FPZ had a significant effect (P<0. 05) on gizzard relative weight. Increasing FPZ significantly (P<0. 05) increased gizzard relative weight. Both FPZ of 1500 μ m AND CZ of 2. 5 mm numerically caused FI reduction, improved FCR, FE, increased EEPF AND reduced abdominal fat weight. The CZ had significant (P<0. 05) effect on relative giz-zard muscular thickness. As the CZ increased, the relative gizzard muscular thickness significantly (P<0. 05) decreased. The effect of CZ on villous high (VH) of ileum was significant (P<0. 05). Indeed, as the CZ in-creased, the VH of Ileum significantly decreased (P<0. 05). A significant interaction (P<0. 05) between FPZ AND CZ was seen in FI, FCR, FE, gizzard relative weight AND relative gizzard muscular thickness, absolute fat weight of gizzard. In the DIET made from the FPZ of 1500 μ m AND CZ of 1. 5 mm FI significantly (P<0. 05) reduced, FE AND FCR significantly (P<0. 05) improved. In conclusion, birds fed coarsely FPZ (1500 μ m) AND smaller CZ (1. 5 mm) DIET showed better FCR AND FE which was due to enhanced gizzard development AND intestinal histomorphology parameters.