The effect of silver nanoparticles as additive on broiler performance was investigated through employed of 312 day-old broiler chiks (Arbor-Acre Plus) in a completely randomized design with 6 treatment diets each in 4 replicates. Corn- soy based diets were formulated for starter, grower and finisher according to NRC (1994) recommendations. The silver nanoparticle solutions (2000 ppm) were added to either diets or drinking water at concentrations of 400 and 800 ml per ton or cubic meter, respectively, to prepare the treatments. Two treatments either with or without antibiotic (flavomycin 500g/t) were considered as control groups. Feed intake and weight gain were weekly recorded. At the end of the experimental period, two birds from each replicate were randomly selected, slaughtered and the weight of carcass, abdominal fat and total digestive organs (total gut tract, caeca and liver) determined. The results showed that different levels of silver nanoparticles in diet and water had not significant effect on broilers performance, but birds fed antibiotic supplemented diet had the highest feed intake and weight gain at the overall rearing period (P<0.05). The level of 800 cc silver nanoparticles in either diet or drinking water significantly increased the relative weight of gastrointestinal tract and liver but decreased the abdominal fat of the broiler chicks (P<0.05). Supplementing diets with antibiotic significantly decreased relative weight of gastrointestinal tract and increased carcass yield. Supplementation of nanosilver particles in diet or drinking water resulted in the retention of these particles in the liver and meat of broiler chicks. The results indicate that silver nanoparticles are not suitable for use as feed additives in poultry nutrition, further studies being needed for more accuarate related information.