Inhomogeneous Magnetization Transfer (ihMT) shows promise as a myelin-specific MRI technique. Recent publications demonstrate that ihMT contrast is generated by long-lived dipolar couplings between protons on lipid molecules. We tested ihMT’s myelin specificity by comparing it to a more validated myelin measure, myelin water fraction (MWF), in 10 healthy volunteers. The ihMT ratio (ihMTR) correlated with MWF in white matter but MWF had a larger dynamic range. When MWF was zero, ihMTR was non-zero, supporting that ihMTR arises from all lipid molecules, not just those in myelin. ihMTR and MWF measure different, and complementary, aspects of tissue structure.