AIM:To investigate the effectiveness of low-volumeplus ascorbic acid [polyethylene glycol plus ascorbicacid(PEG + Asc) ] and high-volume plus simethicone[polyethylene glycol plus simethicone(PEG + Sim) ]bowel preparations.METHODS:A total of one hundred and forty-fourout patients(76 males) ,aged from 20 to 84 years(me-dian age 59.5 years) ,who attended our Department,were divided into two groups,age and sex matched,and underwent colonoscopy. Two questionnaires,onefor patients reporting acceptability and the other forendoscopists evaluating bowel cleansing effectivenes saccording to validated scales,were completed. Indications,timing of examination and endoscopical findings were recorded. Biopsy forceps were used as a measuring tool in order to determine polyp endoscopic sizeestimation. Difficulty in completing the preparation wasrated in a 5-point Likert scale(1 = easy to 5 = un-able) . Adverse experiences(fullness,cramps,nausea,vomiting,ab dominal pain,headache and insomnia) ,number of evacuations and types of activities performed during preparation(walking or resting in bed) were also investigated.RESULTS:Seventy-two patients were selected for eachgroup. The two groups were age and sex matched aswell as being comparable in terms of medical historyand drug therapies taken. Fourteen patients droppedout from the trial because they did not complete the preparation procedure. Ratings of global bowel cleansing examinations were considered to be adequate in91% of PEG + Asc and 88% of PEG + Sim patients.Residual Stool Score indicated similar levels of amountand consistency of residual stool;there was a significant difference in the percentage of bowel wall visuali-zation in favour of PEG + Sim patients. In the PEG +Sim group,12 adenomas ≤ 10 mm diameter(5/left co-lon + 7/right colon) vs 9(8/left colon + 1/right colon) in the PEG + Asc group were diagnosed. Visualization of small lesions seems to be one of the primary advantages of the PEG + Sim preparation.CONCLUSION:PEG + Asc is a good alternative solution as a bowel preparation but more improvements arenecessary in order to achieve the target of a perfect preparation. AIM: To investigate the effectiveness of low-volume plus ascorbic acid [polyethylene glycol plus ascorbic acid (PEG + Asc)] and high-volume plus simethicone [polyethylene glycol plus simethicone (PEG + Sim)] bowel preparations. METHODS: A total of one hundred Two patients, one for patients (76 males), aged from 20 to 84 years (me-dian age 59.5 years), who attended our Department, divided into two groups, age and sex matched, and underwent colonoscopy. reporting acceptability and the other forendoscopists evaluating bowel cleansing effectivenes saccording to validated scales, were completed. Indications, timing of examination and endoscopical findings were recorded. Biopsy forceps were used as a measuring tool in order to determine polyp endoscopic size optimization. Difficulty in completing the preparation wasrated in a 5-point Likert scale (1 = easy to 5 = un-able). Adverse experiences (fullness, cramps, nausea, vomiting, ab dominal pain, headache and insomnia), number of evacuations and types of activities performed during preparation (walking or resting in bed) were also carried investigated .RESULTS: Seventy-two patients were selected for eachgroup. The two groups were age and sex matched aswell as being comparable in terms of medical historyand drug therapies. Fourteen patients droppedout from the trial because they did not complete the preparation procedure. Ratings of global bowel cleansing examinations were considered to be adequate in91% of PEG + Asc and 88% of PEG + Sim patients. Residual Stool Score showed similar levels of amountand consistency of residual stool; there was a significant difference in the percentage of bowel wall visualization in favor of PEG + Sim patients. In the PEG + Sim group, 12 adenomas ≤ 10 mm diameter (5 / left co-lon + 7 / right colon) vs 9 (8 / left colon + 1 / right colon) in the PEG + Asc group were diagnosed. Visualization of small lesions like to be one of the primary advantages of the PEG + Sim preparation. +Asc is a good alternative solution as a bowel preparation but more improvements arenecessary in order to achieve the target of a perfect preparation.