Increased knowledge of the physiological basis behind the signal enhancement in tumors during dynamic contrast‐enhanced magnetic resonance (MR) imaging may be useful in development of predictive assays based on this technique. In the present work, the relative signal intensity (RSI) increase in gadopentetate dimeglumine (Gd‐DTPA)‐enhanced MR images of patients with cervical carcinoma was related to tumor perfusion, vascular density, cell density, and oxygen tension (pO₂). The patients were subjected to MR imaging before the start of treatment (N = 12) and after two weeks of radiotherapy (N = 8). Perfusion was determined from the kinetics of contrast agent in tumors and arteries, vascular density and cell density were determined from tumor biopsies, and pO₂ was determined by polarographic needle electrodes. The maximal RSI was correlated to perfusion (P = 0.002) and cell density (P = 0.004), but was not related to vascular density. There was also a correlation between pO₂ and perfusion (P < 0.001). Moreover, pO₂ tended to be correlated to cell density (P = 0.1), but was not related to vascular density. There was a significant correlation between RSI and pO₂, regardless of whether the median pO₂ (P < 0.001) or the fraction of pO₂ readings below 2.5 mmHg (P < 0.001), 5 mmHg (P < 0.0001), or 10 mmHg (P < 0.001) was considered. Our results suggest that the Gd‐DTPA‐induced signal enhancement in MR images of cervical tumors is influenced by both perfusion and cell density. These parameters are also of major importance for tumor oxygenation, leading to a correlation between signal enhancement and oxygenation. Dynamic contrast‐enhanced MR imaging may therefore possibly be useful in prediction of treatment outcome. J. Magn. Reson. Imaging 2001;14:750–756. © 2001 Wiley‐Liss, Inc.