The current report presents a case of late-onset systemic lupus erythematosus (SLE). A 75-year-old Caucasian woman was admitted to the clinical hospital because of dyspnea, dry cough, low-grade fever, wrist pain. There were no oral and skin lesions or lymphadenopathy observed. Laboratory tests revealed hypochromic microcytic anemia with hemoglobin 111 g/l, lymphopenia 0,54 x 10/l, the erythrocyte sedimentation rate (ESR) elevation up to 47 mm/h and the C-reactive protein level up to 10,7 mg/l. Tumor markers (CA-125, CA-19.9, СА-15,3, α-fetoprotein) concentration, hepatic and renal function were within the reference ranges. Of note, urinalysis didn’t reveal proteinuria or microscopic hematuria and was considered normal. Computed tomography revealed bilateral pulmonary consolidation in S10, sacculated pleuritis, solitary lymphadenopathy, and pericardial effusions. Diagnosis of SLE was confirmed based on three clinical signs (synovitis of proximal interphalangeal joints, serositis including pleuritis, hematological disorders: anemia, lymphocytopenia) and positive findings of three immunological tests (anti-double-stranded DNA antibodies [Anti-dsDNA], antinuclear antibodies [ANA], and anti-nucleosome antibodies [ANuA]). This case demonstrates that late-onset SLE may be one of the reasons for the accumulation of pleural fluid in elderly patients.