The objective of this study is Specify and estimate dates cost function and to utilize it's indicators to understand the production performance of date in siwa oasis and to draw some policy implications for dates production. The study relied on primary data. A stratified random sample of 36 farmers representing date producers was selected from siwa oasis. Farm owners sample were interviewed, and primary data were gathered through the interviews in 2014 season. Analytical procedures were utilized in processing and analyzing the data. Multiple regressions were used to reach the basic findings of this research. Cost function was specified and estimated in various functional forms.