Mechanical bowel preparation is routinely done before colorectal surgeries to reduce morbidity and mortality all over theworld. The role of mechanical bowel preparation in preventing complications is recently disputed. The aim of the study was toassess whether elective colorectal surgery can be performed without mechanical bowel preparation. This cross sectionalcomparative study was carried out to assess the role of mechanical bowel preparation in post-operative complications inelective colon and rectal surgery in the department of surgery of Bangabandhu Sheikh Mujib Medical University, DhakaMedical College Hospital and SSMC-Mitford Hospital during year period. Fifty patients undergoing surgery foronecarcinoma of colon and rectum were included in the study. Patients were allocated in two groups by non-probability convenientconsecutive technique-one group with mechanical bowel preparation with polyethylene glycol and one group with nopreparation before surgery. All patients in the study group were followed up for at least one month after surgery for woundinfection, anastomotic leakage and intra-abdominal infection. Total 50 patients were randomly divided into two groups (groupA, 25 patients & Group B, 25 patients). Group A was the preparatory group and Group B was the non-preparatory group. Thetype of surgical procedure and the type of anastomosis did not differ significantly between two groups. Sixty percent patients ofgroup A developed post-operative complications; on the other hand fourty percent patients of group B developed post-operative complications. This study concluded that no advantage is gained by pre-operative mechanical bowel preparation andcan be easily avoided in order to save the patient from unwanted events like nausea, vomiting, electrolyte imbalance and alsoincreased chance of post-operative complication.