This study was assessed to detect and diagnose cryptosporidium parasite of chickens (Galluas gallus) using three especial stains (Modified Zeihl-Neelsen, Giemsa's, and Saffranin methylene blue stains) by direct smears. In this study (80) fecal droppings were collected from chickens at different ayes and sexes used chickens suffered from emaciation non bloody diarrhea raffled feat theirs and respiratory disorders with nosal discharge. Accurate diagnosis was optioned using Ziehl-Nelsecnstain (62.27) cereyiored to saffranin methylene blue stains 20% and Giemsa stain 15%. Scrapings and imprints of small intestine trachea and Bursa of fabricous from (20) necropsied birds, revealed 18.3% infection in the small intestine, 8.4% in trachea and 1.6% in Bursa of Fabricous. The results of microscopic examination of cytological smears were more sensitive and accurate for oocyst of cryptosporidia by modified Ziehl-Nelseen stain, than by Saffranin methylene blue stains, and Giemsa stain. For study of histopathological changes of this protozoa in infected tissues 10 samples were collected from small intestine, trachea and Bursa of Fabricous from necropsed birds and fixed, stained with Haematoxylene – Eosine stain, the main pathologic changes of small intestine were atrophic misshapen villi and with infiltration of Lamina properia with inflammatory cells. In Trachea mucinous degeneration, deciliation and sloughing. In Bursa of Fabricous the changes involve depletion of lymphocyte. Microscopic examination of 10 samples from small intestine trachea and Bursa showed that the small intestine were atrophic with misshapen vulli and cellular infection of the commproperia muanous degeneration defilation and sloughing of tracheal epith.