The presence of bowel contents during colorectal surgery has been related to surgical site infections (SSI), anastomotic leakage (AL) and postoperative complications theologically. Mechanical bowel preparation (MBP) for elective colorectal surgery aims to reduce fecal materials and bacterial count with the objective to decrease SSI rate, including AL. Based on many observational data, meta-analysis and multicenter randomized control trials (RTC), non-MBP did not increase AL rates or SSI and other complications in colon and even rectal surgery. In 2011 Cochrane review, there is no significant benefit MBP compared with non-MBP in colon surgery and also no better benefit MBP compared with rectal enemas in rectal surgery. However, in surgeon's perspectives, MBP is still in widespread surgical practice, despite the discomfort caused in patients, and general targeting of the colon microflora with antibiotics continues to gain popularity despite the lack of understanding of the role of the microbiome in anastomotic healing. Recently, there are many evidence suggesting that MBP+oral antibiotics (OA) should be the growing gold standard for colorectal surgery. However, there are rare RCT studies and still no solid evidences in OA preparation, so further studies need results in both MBP and OA and only OA for colorectal surgery. Also, MBP studies in patients with having minimally invasive surgery (MIS; laparoscopic or robotics) colorectal surgery are still warranted. Further RCT on patients having elective left side colon and rectal surgery with primary anastomosis in whom sphincter saving surgery without MBP in these MIS and microbiome era.