A recent ultrasound imaging technique, called shear wave elastography, showed its ability to image and quantify mechanical properties of biological tissues, such as prostate or liver. In the present study this technique was used to evaluate the relation between tumor growth, stiffness and tumor reduction upon treatment with combretastatin (CA4P) in allografted colon tumor CT26, in mice. During twelve days, CT26 tumor growth (n=52) was imaged by ultrasound, and shear modulus was quantified, showing a good correlation between tumor volume and stiffness (r = 0.59). At day 12, the treatment was initiated and monitored every day during 4 days. Following the treatment, the tumor volume has decreased, still the elasticity parameter of the tumor volume was steady throughout the treatment. After segmentation using the shear modulus map, a detailed analysis showed a decrease in the stiffness after treatment as compared to the control group. This reduction in the mechanical properties was shown to correlate with tissue reorganization, in particular fibrosis and necrosis, assessed by histology.