Background: To perform a one-stage operation safely in selected patients with left-sided colonic obstruction, many surgeons have considered intraoperative colonic irrigation as an indispensable step. Recently, studies have shown that step is unnecessary. The aim of this study was to identify the early results of a one-stage operation without intraoperative colonic irrigation in the treatment of left-sided colonic obstruction. Methods: This case series included patients who had resectable left-sided colonic obstruction and were admitted to Nhan Dan Gia Dinh Hospital from January 2008 to December 2018. All patients were treated by one-stage operation without intraoperative colonic irrigation. The early results were described, focusing on mortality, anastomotic-related complications, operative time and length of hospital stay. Results: There were 74 patients with a mean age of 50 years (range 20–81 years). Colorectal cancer accounted for 86.4% of cases. The median operative time was 158 ± 42 min (range 65–285 min). One patient (1.4%) died on postoperative day 6 due to pneumonia and multiorgan failure. Three patients (4.1%) had major anastomotic leakage, 4 patients (5.4%) had minor anastomotic leakage, 9 patients (12.2%) had wound infection, 4 patients (5.4%) had intraabdominal fluid collection, and 1 patient (1.4%) had an early adhesive small bowel obstruction. The median length of hospital stay was 9 ± 3 days (range 5–24 days). The method was successful in 70/74 patients (94.6%). Conclusions: With properly selected patients and experienced GI surgeons, a one-stage operation without intraoperative colonic irrigation is an effective and safe alternative for resectable left-sided colonic obstruction. Highlights: