The paper describes a rare clinical case of rheumatoid arthritis (RA) that developed in a patient 9 years after diagnosing IgA nephropathy. Kidney disease was characterized by a stable course with moderate urinary syndrome, hypertension, and reduced renal function. Immunosuppressive therapy using glucocorticosteroids and then mycophenolic acid led to remission of nephritis and recovery of renal function. However, the absence of nephritis activity and discontinuation of immunosuppressants was responsible for articular syndrome. The diagnosis of RA is based on its characteristic radiological patterns and immunological characteristics after ruling out a number of systemic diseases and infections. The common pathogenetic components of IgA nephropathy and RA, including the role of rheumatoid factor IgA, are discussed.