In the present study shrimp shell and chitosan due to low economic value and availability were used and optimized the absorption of oxytetracycline (OXT) in aquaculture effluent byresponse surface experimental design. The effects of simultaneous fourIn the present study shrimp shell and chitosan due to low economic value and availability were used and optimized the absorption of oxytetracycline (OXT) in aquaculture effluent by important variables involves: the initial concentration of oxytetracycline (10, 30 and 50 mg), pH of the solution containing oxytetracycline (2, 5 and 8), amount of adsorbent (10, 55 and 100 mg l) and temperature (15, 25 and 35 ?C) on the adsorption efficiency of oxytetracycline using a box - Bnkn design, test and analysis of variance procedures, response plans, were used to validate the proposed model. the proposed model (Quadratic equation) for this study, was confirmed according to the analysis ANOVA. Also, the method of high performance liquid chromatography (HPLC) was used to determine the amount of oxytetracycline remained in the solution after passing through the adsorber. Surface morphology, funtional groups and specific surface area (BET) of shrimp shell and chitosan as adsorbent, before and after adsorption were investigated using Scanning Electron Microscopy ( SEM ), Fourier Transform InfraRed (FT-IR). According to the results of the experiments for both adsorbents, the adsorption efficiency of oxytetracycline increased with: lower concentrations of oxytetracycline from 50 to 10 mg, increasing the initial pH of the solution containing oxytetracycline from 2 to 8, the amount of adsorbent to approximate from 10 to 100 mg, and temperatures from 15 to 35 ?C. Regression equations derived from analysis of data for the absorption of tetracycline by shrimp shell and chitosan, respectively, with determination coefficient 0.9879 and 0.9899 are as follows indicating the absorption of pseudo-second-order model. In the optimized experimental conditions, the maximum yield of oxytetracycline absorption by shrimp shell and chitosan were 73.6 and 82.8, respectively. The results clearly indicated that a greater ability of chitosan to adsorber oxytetracycline in aqueous solution than shrimp shell, which was due to the higher specific surface (results BET) and most of the pores (results of the SEM ) chitosan to the shell of shrimp. Keywords : Biosorption, chitosan, shrimp shell, Response surface methodology, Box-Behnken, SEM, BET, HPLC, FT-IR