Two hundred Muscovy hatched ducklings were used, at 5 weeks of age, randomly divided into three groups : group (1) was fed a control diet all over the experimental period, group (2) was fed the control diet supplemented with 5 % sunflower oil from 5 to 12 weeks of age, group (3) fed as group 2 up to 8 weeks of age, then birds were fed the control diet supplemented with 7.5 % sunflower oil from 9 to 12 weeks of age. Feed and water were offered ad libitum during the experimental period. Live body weight of birds was individually recorded each week from hatching to the end of the experiment (12 weeks). All of the gain in body weight, feed consumption (gm / bird) and feed conversion (gm feed / gm body weight gain) were recorded. However, two males and two females from each group at 4, 8 and 12 weeks of age were taken randomly through the experimental period for determining body and carcass characteristics. Live body weights of ducks were recorded before slaughtering. The birds were plucked, eviscerated and weighted and all of : body circumference, shank length, thigh length; along with absolute and relative weights of : carcass, giblets (gizzard, heart, liver), neck, inedible parts (blood, feather, alimentary canal, head, shank), giblets  abdominal fat were determined. Also, dressing %, giblets %, neck %, edible parts %, inedible parts %, and deboning % were calculated. However, the chemical analysis (moisture, fat, crude protein, ash) of breast and thigh meat; and left femur of each duck (slaughtered at 12 weeks of age) were determined. The absolute and relative weights along with absolute and relative lengths of empty digestive tract and its parts (oesophagus, proventriculus, gizzard, duodenum, jejenum and ilium, rectum, caecium) were recorded.           The data revealed that :  Sunflower oil supplementation at 8 and 12 weeks of age by adding either 5.0 % or 7.5 % significantly increased           live body weight, carcass weight %, dressing % abdominal fat, gizzard, carcass fat, thigh ash, body circumference, thigh length, pH of jejunum and ileum contents; and significantly decreased inedible parts %, carcass moisture, carcass protein, bone ash, bone calcium, bone phosphorus, relative wt. of duodenum, relative wt. of jejunum and ileum. While, the sunflower oil supplementation at 8 and 12 weeks of age by adding either 5.0 % or 7.5 % had no effect on giblets %, breast ash, shank length, relative lengths of proventriculus and gizzard, relative length of large intestine, pH of gizzard content; but, sunflower oil supplementation at 8 and 12 weeks of age by adding either 5.0 % or 7.5% decreased liver %, pH of oesophagus and crop contents, pH proventriculus content. However, sunflower oil supplementation at 12 weeks of age by adding 7.5 % increased significantly liver %, heart %, pH of oesophagus and crop contents, pH proventriculus content. Sunflower oil supplementation at 12 weeks of age by adding either 5.0 % or 7.5 % increased deboning %, gizzard %, pancreas %, liver %, pH of caecum contents, pH of rectum contents; and decreased relative wt. of oesophagus and crop, relative length of oesophagus and crop. Sunflower oil supplementation at 12 weeks of age by adding 5.0 % decreased significantly neck %. Sunflower oil supplementation at 8 weeks of age by adding 5.0 % increased neck %, heart %, relative wt. of proventriculus and gizzard, liver %, relative length of jejunum and ileum; and  decreased relative weight of digestive tract, pancreas %, relative length of oesophagus and crop, pH of caecum contents, pH of rectum contents. Generally, sunflower oil supplementation to the diets of ducks improved growth rate and digestibility, and increased final body weight, body measurements and deboning %, and also reduced feed consumption.