The International Myeloma Working Group (IMWG) has revised the International Staging System (ISS) to enable better stratification of newly diagnosed myeloma patients. It now includes the detection of chromosomal abnormalities (CA) by interphase fluorescent in situ hybridisation (iFISH) and the measurement of serum lactate dehydrogenase (LDH) which, when combined with the previous ISS, provides powerful prognostic power compared with the each individual parameter. Based on pooled clinical and laboratory data from 4,500 patients participating in 11 international trials, three groups are defined as: revised ISS (R-ISS), including ISS Stage I, no high-risk CA and normal LDH levels; R-ISS including ISS Stage III and high risk CA or high LDH levels, and R-ISS-II including all other possible combinations. The five-year overall survival was 82, 62, and 40 percent, respectively, in R-ISS I, R-ISS II, and R-ISS III, at a median follow-up of 46 months. Whilst host factors still play an important role in defining patient prognosis, the revised ISS system will be able to stratify newly diagnosed patients more effectively than before with respect to the relative risk of their survival.