A large series of plasma cell dyscrasias (n=2207) was examined for translocations which deregulate the MAF genes, t(14;20)(q32;q12) and t(14;16)(q32;q23), and their disease behavior was compared to a group characterized by the t(4;14)(p16;q32) where CCND2 is also up-regulated. The t(14;20) showed low prevalence in myeloma (27/1830, 1.5%) and smoldering myeloma (1/148, <1%) with a higher incidence in MGUS (9/193, 5% P=0.005). Strong associations with del(13) (76%), non-hyperdiploidy (83%) and gain of 1q (58%) were seen but no association with an IgA M-protein or absence of bone disease was noted. All three translocations were associated with poor outcome in myeloma, but strikingly all t(14;20) MGUS/smoldering myeloma cases (n=10) had stable, low level disease. In contrast, the 10 t(14;16) and 25 t(4;14) MGUS/smoldering myeloma cases were associated with both evolving and non-evolving disease. None of the associated genetic abnormalities helped to predict for progression from MGUS or smoldering myeloma.