This work aimed compatibility and stability studies, five factor and two level (25) full factorial experimental design of immediate release candesartan cilexetil 32 mg tablets. Candesartan cilexetil is a drug substance, which has low solubility and chemical instability properties. Polyethylene glycol (PEG) 4000 showed stability protective property on candesartan cilexetil in tablets. Structural degradation of candesartan cilexetil was prevented by chemical reactions of terminal hydroxyl groups of PEG 4000 with carboxyl, N-H, N=N and anhydride groups of candesartan cilexetil. Stability protective mechanism was realized by converting crystalline candesartan cilexetil to amorphous form inside the amorphous region of PEG 4000. Stability evaluation showed that candesartan cilexetil could be protected ideally by PEG 4000 concentration of 2.5-10 % (w/w) in tablets. Dissolved drug from tablet could be predicted with high capability from statistical model, resulted from experimental design. Thus, stability and dissolution properties of candesartan cilexetil could be controlled in developed tablets.