Background/Aims: Polyethylene glycol (PEG)-based bowel preparations are effective cleansing agents for colonoscopy. However, they require relatively large volumes to be used even with agents such as 2 L PEG with ascorbate (2LPEG). This phase 3, randomized, single-blinded, multicenter, parallel-group study compared the efficacy of 1 L PEG with high-dose ascorbate, TJP-008, to 2LPEG. Methods: Patients undergoing colonoscopy were randomized (1:1:1) to receive TJP-008 as 1-day split dose (TJP-008-1) or 2-day split dose (TJP-008-2) regimen or to receive 2LPEG as a 2-day split dose regimen. Cleansing efficacy was evaluated using the Harefield Cleansing Scale. The primary endpoint was overall bowel cleansing success. Full analysis set (FAS) and per protocol set (PPS) analyses were performed. Results: Of the 314 screened patients, efficacy was assessed in the following patient numbers (FAS/PPS): total (293/285), TJP-008-1 (98/94), TJP-008-2 (97/95), and 2LPEG (98/96). FAS revealed noninferiority between TJP-008 and 2LPEG with regard to overall success (TJP-008-2, 99.0%; TJP-008-1, 95.9%; 2LPEG, 94.9%; p=0.100 and p=0.733, respectively). PPS also showed noninferiority (p=0.721 and p=0.211, respectively). However, the PPS analyses showed a higher bowel cleansing score for TJP-008-2 for high-quality cleansing in the right colon (TJP-008-2 83.2% vs 2LPEG 62.5%; p=0.005). Conclusions TJP-008 is a new low-volume cleansing agent with a colon cleansing efficacy comparable to that of standard 2LPEG that exhibits significant safety and tolerability