Kidney transplantation is the most important therapy for patients with dialysis-dependent renal insufficiency. Delayed graft function is a form of acute renal failure that results in post-transplantation oliguria. Recently, the pathophysiology of renal ischemia, reperfusion injury, vascular or ureteral obstruction has been recognized as the consequence to the development of delayed graft function, but there was a lack of imaging characteristics to demonstrate or interpolate the structural and functional changes of the graft renal parenchyma. There is growing interest in applying the intravoxel incoherent motion (IVIM)-based diffusion weighted imaging (DWI) to extend the clinical applications of DWI, which makes it possible to separate tissue diffusivity and micro-capillary perfusion by a bi-exponential fitting analysis of DWI images with a number of b-values. In this experiment, we attempted to perform intravoxel incoherent motion (IVIM) MRI in 48 hours after renal transplantation and there are some patients coming back to the clinic for following-up condition after six months to evaluate the micro-structural and microcirculation status of graft kidneys. The goal of the present study is to perform IVIM MRI and non-contrast MRI and MRA in patients after renal transplantation to evaluate the micro- and macrocirculation status of graft kidneys. Seventeen patients (10 men, 7 women; mean age 47.0±12.1, range 20-63) with kidney allografts were scanned by a 1.5T wholebody (Aera, Siemens) in 48 hours after renal transplantation and 5 of them had a second scan in six months later. Fast spin echo T1WI, T2WI and IVIM-DWI sequences were acquired in the long-axis coronal section of graft kidneys with the same spatial encoding coordination, except matrix sizes. The Institutional Review Board of TCVGH reviewed and approved the experimental protocol and the consent procedure. Other sequences included 3D-TrueFISP non-contrast MRA, 2D TOF and gated phase-contrast MRA to estimate the macro-circulation of graft kidneys. IVIM sequence was performed by using free-breathing single spin-echo echo-planar-imaging (SE-EPI). The imaging parameters were TR/TE=2000/61ms, FOV=306*306mm, matrix size =128*128, scan time=240 s, nine b-values of 0, 10, 20, 30, 50, 100, 300, 500 and 800 s/mm2.We used varality of algorithms to segment parenchyma part from allograft kidneys of MR images. They can be divided into the renal parenchyma to do analysis. Three IVIM parameters were calculated by using the built-in bi-exponential analysis software in Siemens system (Dr. Bernd Kuhn, Siemens AG, Healthcare), including the diffusion coefficient of slow or non-perfusion-based molecular diffusion (D;um2/ms), which represents pure molecular diffusion; the diffusion coefficient of fast or perfusion-based molecular diffusion (D*;um2/ms), which represents intravoxel microcirculation or perfusion; and perfusion fraction (f or PF; %). In this study, the results showed that mean volume of graft renal parenchyma calculated after segmentation were 144±2.7 mL in 17 patients. For the IVIM-derived parameters, mean f of 17.76±6.3, and mean D of 1.71±0.13 um2/ms and D* of 10.26±3.3 um2/ms. On non-contrast MRA, patent graft arteries and veins were demonstrated. Mean graft renal arterial and venous blood flows were 5.6±2.1 mL/s and 5.6±1.84 mL/s using PC-MRA as shown on Table 1. For comparing the relationship of the macro- and micro-circulations in graft kidneys, there existed a median linear relationship between f values and the values of “the mean arterial flow/graft renal volume (A flow/Volume GK)” (r = 0.567), a weak relationship between D* values and “A flow/Volume GK” values (r = 0.307), and no relationship between D values and “A flow/Volume GK” values (r < 0.1). Comparison of examination in 48 hours after renal transplantation and follow-up after six months, we will know that D and D* values be increased slightly. Otherwise the PF value be decreased on Table 2. And we will found that changes in renal function about CREAT and DW-IVIM parameters values, The D and D* values decreased when the CREAT (creatinine) increase as shown on Table 3. Comparison of successful kidney transplantation and failure cases, the failure cases about D, D*, and PF values decreased because one patient has clinical exclusion and the other one patient has delayed graft function shown on Table 4.The experimental results suggest that diffusion parameters of D*, D and f values in IVIM-DWI might considerably be useful in early detection of functional change graft kidneys and non-contrast MRA and PC-MRI could effectively assess patency and flow rates of graft vessels. Combination of both IVIM-DWI and non-contrast MRA would be potentially promising in clinical application for monitoring graft kidneys.