Four experiments were run in which diets incorporating various levels of n-3 fatty acids (n-3FA) from fish (menhaden) oil or flax seed were tested for their abilities to reduce the severity of Eimeria tenella infections in young broiler chicks. The diets were fed from 1 d of age through 3 wk of age. Chickens were infected at 2 wk of age. Diets consisting of broiler starter ration supplemented with 2.5 to 10% fish oil, 10% flax seed oil, or 10% linseed oil significantly decreased cecal lesions and maintained weight gains as compared to unsupplemented diets. Light micrographs of ceca from chickens that consumed high n-3FA diets showed reduced parasite invasion and development. Short-term feeding of diets high in n-3FA to young chicks may be a practical method for reducing production losses from cecal coccidiosis.