Nuclear magnetic resonance imaging (NMRI) techniques were used for the measurement of the spatial distribution of apertures and two-phase fluid distributions in rock fractures. Rock models of known apertures were used to validate the NMRI technique. NMRI aperture values were in good agreement with nominal and hydraulic aperture values. The fracture signal in porous rock was isolated by NMR spin-spin relaxation times. Areal distributions of oil and water in an immiscible fracture flow were resolved on the basis of their NMR spin-lattice relaxation times.