Bipolar Disorder (BD) is a common, heritable, chronic, and recurrent disorder that represents a critical public health problem, due to its prevalence, its high degree of disability and psychiatric and medical comorbidities (MC). The project on “Medical comorbities in bipolar disorder: clinical validation of risk factors and biomarkers to improve prevention and treatment” (BIPCOM) aims to study MC in people with BD targeting 2 main objectives: (1) to identify prevalence rates, risk and protective factors and natural history of MC among subjects with BD, through analyses of the Nordic medical registers and a cross-sectional study exploiting existing datasets of patients with BD; (2) to conduct a clinical study involving 400 subjects to assess the overall clinical profile of these patients and study the onset of medical comorbidities. BIPCOM will be implemented through continuous consultations with stakeholders (scientific and patients’ associations, users, and families), for ensuring results’ acceptability and transferability.