Abstract: The study was designed as a 2x5 factorial arrangement with main effects of feeding blood meal as a replacement of 0, 25, 50, 75 or 100% of dietary fish meal and the duration of this substitution at 1-42 or 21-42 days of age. One thousand 1 day old male Cobb 500 broiler chicks assigned randomly to each of 40 floor pens (25 birds/pen) and were fed five isonitrogenous and isocaloric feeds formulated to contain 20.38 and 17% crude protein and 2900 and 3000 kcal kg-1 metabolizable for starter and grower periods, respectively. Duration of dietary manipulation didn`t affect the measured parameters. More than 25% blood meal/fish meal substitution ratios significantly increased chickens daily weight gain and decreased the cost of producing a unit of meat. Other traits didn`t affect by dietary fish meal/blood meal replacement ratio. Spleen and proventriculus percents and small intestine length affected by level of replacement but didn`t follow a distinct pattern. These results indicate that this locally produced blood meal is a suitable substitute for dietary fish meal and a full replacement didn`t cause any adverse effect on performance, carcass important traits and dietary nitrogen retention of broiler chickens.