OBJECTIVES: To develop and validate a conceptual model (CM) of multiple myeloma (MM) for use in economic modelling that characterises the disease in terms of attributes that impact on disease progression and outcomes. METHODS: A draft CM was developed using two systematic literature reviews to identify attributes of MM that appeared to impact on disease progression and outcomes. These attributes were grouped according to the aspects they measured (e.g. symptoms) and then linked to denote relationships across groups. This was discussed and validated by a Delphi panel of four MM experts. For simplicity, the CM did not consider the impact of treatment RESULTS: Consensus was reached about the attributes to be included in the CM: baseline and disease characteristics (age, comorbidities, Eastern Cooperative Oncology Group performance status and genetic factors), central associations (disease activity, complications and symptoms) and final outcomes (overall survival [OS], quality of life). Disease activity was measured by several factors, including M-protein and serum lactate dehydrogenase. There was consensus that most genetic factors [e.g. t(4;14), del(13p)] influenced disease activity, which in turn affected complications (e.g. anaemia, renal complications). Symptoms (e.g. pain, bone fractures) were influenced by genetic factors and disease activity. Disease activity, comorbidities and complications impacted on OS. Consensus was not reached for the impact of age/comorbidities on complications/symptoms, nor for the influence of del(17p) on complications. CONCLUSIONS: There was agreement on the attributes that should be used to characterise and understand MM; however, the lack of consensus on the association between some attributes reflects the relatively limited understanding of how aspects of MM impact on disease progression and outcomes. Future studies should focus on understanding the gaps identified. This CM may be used in economic modelling and could form the foundation for developing disease-based MM models to explore the impact of treatment on outcomes.