PURPOSE: The toxicity of postoperative radiotherapy for cervical cancer affects patients' quality of life. We evaluated acute toxicity in postoperative intensity-modulated radiotherapy (IMRT) and three-dimensional conformal radiotherapy (3DCRT) as well as the influence of dosimetric parameters and concomitant chemotherapy. METHODS: A total of 45 patients with early operable cervical cancer underwent postoperative IMRT with 40-45 Gy. The control group of 50 patients was treated with 3DCRT. Brachytherapy and concomitant cisplatin chemotherapy were performed in all patients according to pathologic and histologic findings. The patients were monitored for acute gastrointestinal, urological and hematological toxicity classified according to the RTOG acute radiation morbidity scoring criteria. We also analyzed the influence of dosimetric parameters on acute toxicity. RESULTS: Significant differences were found in overall acute toxicity (p=0.018), acute genitourinary toxicity (p=0.029), anemia (p=0.043) and neutropenia (p=0.027) but not in acute gastrointestinal toxicity between the IMRT and 3DCRT groups. In all patients, regarding chemotherapy administration, differences were found between the chemoradiotherapy and radiotherapy group as far as overall acute toxicity (CHRT vs RT; p=0.011) and hematological toxicity were concerned (p=0.001). Patients with ≥3 cycles of chemotherapy showed increased hematologic toxicity. In the IMRT group according to the administration of chemotherapy (chemoradiotherapy vs radiotherapy), statistically significant difference for leukopenia (p=0.009) was found and in the 3DCRT group for anemia (p=0.021) and neutropenia (p=0.029). According to chemotherapy administration (chemoradiotherapy vs radiotherapy), a statistically significant difference in leukopenia (p=0.009) was found in the IMRT group while in the 3DCRT group the differences were in anemia (p=0.021) and neutropenia (p=0.029). CONCLUSION: IMRT is associated with lower acute toxicity and better dosimetric parameters in organs at risk (OAR) compared to 3DCRT. Higher hematological toxicity occurred when concomitant chemotherapy was performed, regardless of RT technique. Further reduction of toxicity is expected with protocol and technical improvement and research of gene-related toxicity.