A proper bowel preparation is key to a thorough and safe colonoscopy. Several factors affect the mucosal visualization during colonoscopy, and consequently the quality of such evaluation. Undoubtedly, this can have unfavorable implications like missed lesions. One of the most commonly encountered scenarios is the presence of multiple bubbles that interfere with mucosal visualization. When this occurs, simethicone (an antifoam agent used to reduce bloating when ingested orally) is injected through the colonoscope to eliminate the bubbles and get a clear view of the mucosa. A few studies have used oral simethicone in conjunction with oral preparation agents (PEG, magnesium citrate, sodium phosphate) in an attempt to improve the quality of the preparation. Unfortunately these studies have not used the exact same preparation agent with and without simethicone, making it difficult to draw conclusions on its efficacy. However, it is important to understand that simethicone is not intended to decrease the amount of stool in the colon, and it's purpose is to decrease the amount of bubbles interfering with the visualization of the mucosa provided that there is no stool present . Furthermore, it is unclear if adding simethicone to a standard bowel preparation makes a significant difference in key aspects of screening colonoscopy such as adenoma detection rate or withdrawal times. This prospective randomized controlled, observer blinded study at Texas Tech University Health Sciences Center in El Paso, aims at studying the effect of simethicone on the overall colon preparation as well as on adenoma detection rate and withdrawal times.