This research aims to study and determine most important economic factors affecting on Broiler Production farms in Kafer ELsheikh Governorate. In addition  it estimates economic efficiency of Broiler Production farms in The Private Sector in the Governorate, In addition to  the statistical estimation for costs functions in Broiler Production farms especially the studied sample. Furthermore, knowing the problems which Face poultry fattening in the Governorate and also, the solutions suggested it . The study depend on data collected farm stratified random sample of Broiler farms in The Private  Sector in Kafer ELsheikh Governorate in 2021. Moreover, the study depend on descriptive analysis and multiple regression have been applied to estimate the production functions.
       The results obtained are summarized as follows :
1-       The results of study had declared that the most important economic factors affecting Broiler Production are number of chicks, Feed quantity, Farm labor , veterinary cares and value of electricity , water changes .
2- The analysis revealed that farms of the third scale are the most efficient farms, as rendering net revenue per unit (ton broiler production) approaching 172.80% and 117.24% of the farms of the second scale respectively .
3-       The production elasticties estimates , the study indicated that farms of First scale and Second scale of the private sector are working in the first stage of the diminishing return law . with productive elasticties of 1.083 and 1.602 respectively . while farms of Third scale has been working in the second stage with production elasticity of 0.982 .
4- The results of the estimated economic efficiency for the that farms of total sample in the private sector in Kafer ELsheikh Governorate was 2.432 , 5.283, 9.711 , 1.390. 3.044 , 1.715 for inputs number of chicks, Feed quantity. The mattress. Medicines and veterinary car. value of electricity and water. and The volume of human labor respectively
5 - Estimated size of the optimum the production of the farms of First scale  ,  Second scale , Third scale and total sample in the private sector in Kafer ELsheikh Governorate by about 7.69, 8.69 , 36.24 ,  18.44  tons . And the size of output that maximizes profits by about 7.75 , 7.58 ,  43.13 , 29.34  tons  respectively .