Response surface methodology( RSM) was employed to enhance the production of γ-amino butyric acid by marine strain Rhodotorula benthica OY92. A significant influence of MgSO4·7H2O,NaCl,and initial pH onγ-amino butyric acid production was noted with Plackett-Burman design. Then,a three-level Box-Behnken design was employed to optimize the medium composition and culture conditions for the production of the γ-amino butyric acid in shake-flask. Using this methodology,the quadratic regression model of producing γ-amino butyric acid was built and the optimal combinations of media constituents and culture conditions for maximum γ-amino butyric acid production were determined as MgSO4·7H2O 1. 21g / L,NaCl 4. 79 g / L,and initial pH 5. 75. γ-amino butyric acid production obtained experimentally was coincident with the predicted value and the model was proven to be adequate. The enhancement of γ-amino butyric acid from 7. 39 g / L to 13. 89g / L was achieved with the optimization procedure.