The purpose of this study was to quantify the changes of tumor blood flow (BF) in cervical cancer after radiation therapy by using perfusion computed tomography (CT), and to examine the difference between maximum slope (MS) and single-input one-compartment model (SOCM) methods. Fourteen consecutive patients who received definitive radiation therapy for cervical cancer from October 2009 to February 2010 were enrolled in this study. Blood flow (BF) analyses were performed using both MS and SOCM methods. Quantitative BF maps were created using Body Perfusion (Toshiba Medical Systems, Co. Tokyo, Japan). Perfusion color maps were successfully created by the two analytical methods. BF of the tumors was clearly higher than that of normal cervix, making it possible to distinguish tumor tissue from normal cervical tissue. BF of the tumors after 20 Gy of radiation therapy calculated by the MS method was significantly larger than that before treatment (126.9 vs. 72.2 ml/min/100 ml, median; p < 0.05). Although BF calculated by the MS and SOCM methods showed a positive linear correlation (p < 0.001, r = 0.981), BF calculated by the MS method was lower than that obtained by the SOCM method (103.7 vs. 115.1 ml/min/100 ml, p < 0.01). The change of tumor BF in cervical cancer before and after radiation therapy can be monitored by conducting blood flow analysis using perfusion CT. BF by the MS method was lower than that by the SOCM method, but the two analytical methods correlated well. Perfusion CT may have potential in noninvasive monitoring of vascular and oxygenation status and for guiding adaptive therapy.