The role and value of texture analysis in the quantification of medical images is reviewed and the various methods described. The promise in magnetic resonance imaging is discussed and the coordinated research programme being carried out within the framework of the European Economic Community Concerted Action on Tissue Characterization by MRS and MRI is outlined. Tissue characterization of the human brain has been performed by texture analysis of proton relaxation time images using a standard MR whole body imager operating at 1.5 T and the results are presented.