T1 methods - inversion recovery (IR) spin-echo EPI, IR balanced fast field echo (bFFE), MOLLI 5(3)3, and variable flip angle mapping - are compared for the assessment of renal cortex and medulla T1. IR SE-EPI and IR bFFE allow multi-slice assessment using respiratory triggering, whilst MOLLI and VFA are collected in breath-holds. Compared with IR SE-EPI, MOLLI is in agreement (bias -53ms), IR bFFE is lower (bias -177ms) and VFA significantly overestimates T1 (bias +350ms). MOLLI T1 is shown to vary with simulated heart rate. Histogram analysis for the IR SE-EPI T1 map allows differential regions within the medulla to be separated.