Functional kinking due to tethering of iliac arteries by adjacent fibrotic tissue may occur in kidney graft recipients when sitting, and in turn lead to repetitive graft hypoperfusion. The aim was to investigate if perfusion and oxygenation were changed in transplanted kidneys during leg flexion (>90°) compared to the straight-leg position by employing fMRI (DWI, BOLD, ASL). Contradicting our hypothesis, perfusion increased in flexed leg compared to straight-leg position. Furthermore, furosemide had a significantly lower impact on R2*-values in flexed than in straight leg position. In conclusion, results demonstrated an acute impact of strong leg flexion on functional renal parameters.