Abstract The aim of the study was to compare incidences of late gastrointestinal adverse events and clinical outcomes between 3D conformal radiation therapy (3DCRT) and intensity-modulated radiation therapy (IMRT) after radical hysterectomy for cervical cancer patients. Between March 2007 and May 2014, 73 cervical cancer patients with high-risk prognostic factors (pelvic lymph node metastasis and/or parametrial invasion) underwent postoperative pelvic radiation therapy (RT) after radical hysterectomy. Of these patients, 33 (45%) and 40 (55%) received 3DCRT and IMRT, respectively. Because the gastrointestinal obstruction rate after postoperative pelvic 3DCRT was high, no concurrent chemotherapy was applied until 2015. The median follow-up period for patients with 3DCRT and IMRT was 82 months (6–113) and 50 months (5–74), respectively. There was no significant difference in overall survival (OS) (4-year OS: 85% vs 78%, P = 0.744) or disease-free survival (DFS) (4-year DFS: 73% vs 64%, P = 0.696) between the two groups. Eleven (33%) and 13 (33%) patients experienced recurrence after 3DCRT and IMRT, respectively. The patients who had vaginal invasion from the postoperative pathological finding more frequently had loco-regional recurrence than the patients who did not have vaginal invasion (2.3% vs 17%, P = 0.033). Gastrointestinal obstruction was observed in 9 (27%) and 3 (7.5%) patients for 3DCRT and for IMRT, respectively (P = 0.026). Severe gastrointestinal obstruction that required surgery was observed in 6 (19%) patients, all of whom received adjuvant RT by 3DCRT. IMRT could reduce the incidence of late severe gastrointestinal obstruction after postoperative pelvic RT with a non-inferior clinical efficacy compared with 3DCRT.