Introduction: Rheumatic diseases (RD) are conditions with a variety of clinical manifestations and prognosis influenced by several factors. Cohorts and registries have been already established in some countries and have contributed to important knowledge about the disease course and the long-term outcomes of RD. This paper introduces the CoReumaPt project and sets the first step towards the creation of a prospective cohort study including the main RD occurring in the Portuguese population. CoReumaPt will allow outcomes research of chronic RD and the assessment of factors influencing the development and progression of RD. It will also allow to further evaluate the economic impact and the burden of RD in Portugal. CoReumaPt will be linked to Reuma.pt, the National Register of Rheumatic Diseases from Portuguese Society of Rheumatology. Methods: An open cohort will be created, initially composed by the randomly selected population of the cross-sectional National Epidemiological Rheumatic Diseases study (EpiReumaPt) and afterwards by other sources, namely through self- and physician''''''''s referral. Follow-up with annual self-administered questionnaires will be performed, in order to systematically collect and analyze outcomes of interest, mainly patient-reported outcomes. Data concerning less frequent assessments, such as radiographs and biomarkers, will also be assembled. Conclusions: CoReumaPt will be a valuable resource for scientific research and will deliver pivotal information to improve public health policies concerning the prevention and the management of RD in Portugal.