A cross sectional study was conducted from November 2014 to April 2015 with thernobjective to determine hematological and pathological changes on local, Isa brown andrnkoekoek breeds of chickens naturally infected with coccidosis. The study involvedrnhematological, post mortem, mucosal scraping, gross and histopathological examinations.rnA total of 113 chickens with clinical signs suggestive of coccidiosis were examined. FivernEimeria species namely: E. tenella (48.8%), E. necatrix, (11.9%), E. brunetti (10.4%), E.rnmaxima (6%) and E. acervulina (3%) were identified. Reduction on the red blood cells,rnHemoglobin and decreased packed cell volume values were seen due to the effect of thernparasites. From a total of 113 chickens examined, 67 (59.3%) were positive for Eimeriarnspecies. Fifty three (79.1%) of the coccidian positive chickens, showed visible grossrnlesions in the intestine and caecum. The frequency of detection of gross lesions inrnkoekoek breed was significantly higher than that of local and Isa brown breeds (Ï‡2 =rn20.731, p < 0.05). Comparisons were made between microscopic & gross lesions fromrnsmall intestine and caecum and it was found that certain lesions that were graded as mildrnin gross examinations showed significant microscopic lesion. Histopathologicalrnexaminations of the affected small intestine and caecum showed excessive tissue damage,rnsevere hemorrhagic enteritis with epithelial necrosis, presence of large clusters ofrnschizonts and meronts in the damaged epithelial cells along with infiltratingrninflammatory cells especially of eosinophils. In conclusion, the present study showed thatrncoccidiosis had a destructive effect on chickens that is represented by a high reduction inrnred blood cell, packed cell volume, hemoglobin, increment in leukocyte counts andrnvarious gross and microscopic lesions. Prevention and control methods need to bernimplemented to reduce the loss due to coccidiosis.