The present study was aimed to develop modified rel ease pellet of Omeprazole (OMP) applying various to ols of Quality by Design (QbD). Sugar spheres were drug la yered, barrier coated, extended coated and enteric coated in a fluid bed coater to achieve drug release extension. Based on previous knowledge and initial experiment al data, failure mode and effect analysis (FMEA) method were further applied in the risk analysis for the param eters of pellets formulation. Central composite design (CCD ) was employed to optimize OMP pellets selecting in dependent variables (% TEC in ER coat, % Enteric coat, % Exte nded coat) and responses (% drug release at 2, 4 an d 8 hrs. Statistical analysis exhibited that the most signif icant factor affecting Y 1 was X 2 . Factor X3 had significant negative effect on drug release at 4 hrs and 8 hrs which can be mathematically proved by regression equation of Y 2 and Y 3 . Results of physicochemical characterization of OMP pellets revealed compendia compliance. Results of s hort term stability study indicated stable characteristics of developed formulation.