Non-rigid image registration plays a significant role in medical imaging domain. It involves deformations of moving image pixels according to fixed or reference image anatomy. The accurate image registration is required for accurate medical diagnosis and clinical applications. Non-rigid image registration uses optimization technique to find best possible solution. The solution obtained using single run of non-rigid image registration may be optimal but not much accurate. In order to increase accuracy in non-rigid image registration, multiple runs are required to improve the performance. Here in our research methodology, we used Demon algorithm as non-rigid image registration for brain MRI images of patient with tumor. There is significant improvement i.e., average of 66.61% decrease in error of the results of iterative Demon algorithm as compared to non-iterative Demon algorithm.