Radiological skeletal survey or computed tomography are currently applied to assess bone diseases in patients with monoclonal plasma cell disorders. Whole-body magnetic resonance imaging (whole-body MRI) allows detecting the infiltration of clonal cells in nearly the whole bone marrow compartment even before bone destruction has occurred. Those MRI results (i.e., patterns of bone marrow infiltration) have been demonstrated to be of prognostic significance in patients with symptomatic as well as asymptomatic multiple myeloma. We have therefore analyzed the findings of whole-body MRI in 137 consecutive individuals with monoclonal gammopathy of undetermined significance (MGUS). A focal infiltration pattern was detected in 23.4% of patients. Presence and number of focal lesions as well as value of M-Protein were of independent prognostic significance for progression into a symptomatic disease requiring systemic treatment (P=0.02; P<0.0001 and P=0.0005, respectively). Lower homogeneous signal intensities in T1-weighted images were related to a physiologically higher bone marrow cellularity in younger individuals (P=0.002). We conclude that whole-body MRI identifies patients with focal accumulations of presumably monoclonal cells in bone marrow with prognostic impact concerning the risk of progression into symptomatic disease.