Objective To explore the optimal bowel preparation for capsule endoscopy(CE). Methods 102 patients were recruited for CE and randomly divided into 3 groups. The group A(n = 40) : patients received polyethylene glycol electrolyte powder(PEG) 137.12 g dissolved in 2 000 ml water at 21:00 one day prior to CE, and taken PEG 68.56 g dissolved in 1 000 ml of water four hours before the procedure. Group B(n = 32): patients received PEG 205.68 g dissolved in 3 000 ml of water four hours prior to CE. Group C(n = 30)...