Objective: Breast Cancer (BC) is the most frequently diagnosed malignancy worldwide. Not only may BC be associated with rheumatic symptomsand diseases, but also the drugs used in the treatment of this disease, including aromatase inhibitors (AIs), may lead to musculoskeletal system symptoms.In this study, we aimed to investigate the spectrum of rheumatic symptoms and diseases developing in patients with BC having no previous diagnosisof any inflammatory rheumatic disease.Materials and Methods: Patients with a history of BC referring to Rheumatology Outpatient Clinics with complaints of musculoskeletal systemsymptoms at two centers between 2008 and 2018 were screened retrospectively. Patients with a previous diagnosis of any inflammatory rheumatic diseasesbefore the occurrence of BC were excluded. Demographic data, onset and duration of BC, as well as onset and duration of rheumatic symptoms/diseases were recorded. Relevant laboratory tests, including autoantibodies, available imaging findings and the treatments received were also registered.Results: Mean age of 128 BC patients at the time of admission was found to be 54.76±8.21 years. Mean durations of disease for BC and rheumaticdisorders were 85.705±15.507 and 60.84±19.20 months, respectively. Out of 128 BC patients, nearly one third (n: 41; 32.03%), developed an inflammatoryrheumatic disease, and rheumatoid arthritis was the most frequent pathology. Nonspecific arthralgia and myalgia were more frequent in patientsreceiving AIs than those receiving tamoxifen, despite lack of significant difference (p=0.421, p=0.411).Conclusion: Given that nearly one third of the patients developed an inflammatory rheumatic disease, it should be remembered that locomotorsymptoms in patients with BC may be caused not only by bone metastasis or paraneoplastic effects, but they may also suggest the presence of associatedrheumatic diseases.