The aim of this study was to analyze tumor control and clinical outcomes of patients with uterine cervical cancer treated by chemoradiotherapy according to pelvic lymph node (PLN) positivity and boost irradiation to PLN and to determine toxicities associated with boost irradiation.We retrospectively reviewed patients with uterine cervical cancer treated with chemoradiotherapy between March 2000 and April 2015. Clinical characteristics, failure pattern, and survival outcomes of patients with or without PLN metastasis and those with or without boost irradiation were analyzed.A total of 80 cases were PLN-negative and 46 were PLN-positive. A total of 11 patients underwent PLN boost irradiation. The 2-year and 5-year overall survival (OS) rates showed significant difference between the PLN-positive and PLN-negative groups (P = .010). The 2-year and 5-year progression-free survival (PFS) rates showed significant difference between the 2 groups (P = .032). The 2-year and 5-year OS rates of the no-boost irradiation group were 82.9% and 58.3%, respectively, whereas all patients in the boost irradiation group were alive at the time of analysis (P = .065). There was no recurrence in the boost irradiation group. The difference in PFS was significant between the boost and the no-boost irradiation groups (P = .023). The 2-year and 5-year pelvic-recurrence free survival (PRFS) did not show significant difference but the tendency of increased risk of pelvic recurrence in no-boost group (boost vs no-boost; 81.9% and 70.2% vs 100% and 100% in 2-year and 5-year PRFS, respectively, P = .156). Boost irradiation to PLN could improve locoregional control especially in large pelvic LN (≥1.5 cm). Our results showed that only 1 acute and late toxicity of higher than grade 3 occurred.PLN metastasis was significant prognostic factor in cervix cancer treated by chemoradiotherapy. In the boost irradiation group, there was no recurrence or death with significantly better PFS. Boost irradiation to PLN is expected to improve locoregional control, but further follow-up and assessment are needed.