To study the effects of phytase, vitamin E and organic selenium suplementation in broiler fed with low phosphorus on fattening performance and carcass characteristics, 396 one-day old Ross 308 broiler genotype chicks were divided in. six groups with three subgroups in each group. The chicks were fed on isocaloric and isonitrogenic concentrated diets for 42 days. Groups were fed with diet which had adequate available phosphorus (PC: Positive control); inadequate available phosphorus (NC: Negative control); NC+phytase (NC+P); NC+P+ vitamin E (NC+P+vitE); NC+P+organic selenium (NC+P+Se) and NC+P+vitE+Se, respectively. NC diet adversely affected (P<0.05) body weight, daily live weight gain (DLWG) and feed intake, death rates, thigh, breast wing, back weighs and dressing percentage of chicks, which were improved with addition of phytase in diets (especialy NC+P). In conclusion, the addition phytase and phytase+selenium to the diets having low phosphorus increased fattening performance and decreased mortality.