One-dimensional Na-23 NMR imaging (MRI) has been used to follow the ingress of sodium ions into post-rigour porcine muscle during brining. The ingress is well described by Fick＇s second law, with an inter-diffusion coefficient that decreases exponentially with the sodium ion content (between 8 and 20 mg g(-1) cured pork). It is suggested that this decrease is enhanced by the increasing electrostatic charge of the meat proteins and by the dissolution of myosin into solution that accompanies the increase of the NaCl concentration in cured pork.