PURPOSE: The purpose of this study was to compare the tumor shrinkage between radiotherapy alone and concurrent chemoradiotherapy before intracavitary brachytherapy (ICBT). MATERIALS AND METHODS: Nineteen consecutive patients (three stage IB2, nine stage IIB, seven stage IIIB) were selected for measurement of tumor regression. Ten patients underwent radiotherapy alone, and nine patients underwent concurrent cisplatin-based chemoradiotherapy. The average dose of pelvic radiation was given at 45 Gy over a 5-week period in both groups. Computed tomography-based tumor measurement before treatment was compared with measurement after treatment but before intracavitary brachytherapy. The largest width and thickness of the cervical mass were measured from the axial computed tomographic images. RESULTS: Tumor regression before intracavitary brachytherapy varied widely, ranging from 15% to 65%. However, the tumor regression in patients who underwent chemoradiotherapy was higher, ranging from 41% to 65% (mean, 55%), compared with radiotherapy alone, which ranged from 15% to 52% (mean, 38%). CONCLUSION: Our results show that significant tumor shrinkage occurs with concurrent chemoradiotherapy compared with radiotherapy alone. This finding supports the results of recent clinical trials demonstrating improvement of pelvic control and survival with concurrent chemoradiotherapy for advanced cancer of the cervix.