The aim of the present study was to compare 2 different bowel preparations procedures (split-dose with PicoPrep and bisacodyl vs. same-day preparation with PicoPrep) in patients undergoing colonoscopy with regard to quality of bowel preparation, compliance, and willingness to repeat. A retrospective quasi-experimental investigation was conducted. Adults with outpatient diagnostic and surveillance colonoscopies were included. A total of 540 patients participated: group ‘split-dose with bisacodyl’ (n = 293) and group ‘same-day’ (n = 247). Patients in group ‘split-dose with bisacodyl’ had a higher chance for having an excellent quality of bowel preparation (21.2%; 95% CI [13.5, 28.9]) and a reduced risk of an incomplete colonoscopy (4.1%; 95% CI [1.2, 7.0]). Group ‘split-dose with bisacodyl’ drank more fluid, had more nightly visits to the bathroom, and had more bathroom stops on the way to the endoscopic site. No differences were found between groups regarding adenoma detection rate, withdrawal time, overall time of colonoscopy, well-being during cleansing, patient satisfaction, the professional's assessment of the patient's tolerability of colonoscopy, and willingness to repeat the bowel preparation process. The split-dose regimen with PicoPrep and bisacodyl is now the standard bowel preparation procedure for patients undergoing elective colonoscopy as it is superior to the same-day regimen with PicoPrep regarding colon cleansing and incomplete colonoscopy. Hence, the written and verbal information at our institution regarding the bowel preparation procedure was altered according to the split-dose regimen, emphasizing the importance of adequate oral fluid intake and complete intake of the solution in order to ensure a safe and effective procedure.