Background/aim: The aim of this study was to investigate the efficacy of a through- the-scope sodium phosphate solution with completion colonoscopy on the same day as a salvage option for inadequate bowel preparation Materials and methods: All participants were instructed to eat a low residual diet for 3 days before the scheduled colonoscopy and a clear liquid diet 18 h before the colonoscopy. The patients were asked to take split doses of an oral sennoside solution at 1800 and 2200 in the evening before the colonoscopy. In cases of inadequate bowel preparation detected during routine colonoscopy, a sodium phosphate solution was administered through the scope on the day of the colonoscopy procedure. The degree of bowel cleansing was assessed by the Boston Bowel Preparation Scale (BPS: 0?9). Results: Almost excellent bowel cleansing was obtained with a statistically significant difference between the degree of bowel cleansing before and after the application of the sodium phosphate (Boston BPS: 5.48 < 1.01 vs. 8.88 ± 0.33 respectively, P < 0.001). Conclusion: Through-the-scope sodium phosphate with completion colonoscopy on the same day was shown to be an efficacious and acceptable method for inadequate bowel preparation.