Plasma cell disorders, including multiple myeloma, are a group of diseases characterized by the abnormal proliferation of plasma cells. While pleural effusion is uncommon in multiple myeloma, it may result from myelomatous infiltration of the pleura or heart failure due to amyloidosis. In this report, we present a case of a 62-yearold male who was diagnosed with multiple myeloma after presenting with progressive dyspnea, cough, and generalized weakness over two months. Physical examination revealed diminished breath sounds over the left hemithorax. Chest X-ray and ultrasonography confirmed moderate pleural effusion, with 1000 mL of serosanguinous fluid aspirated. Pleural fluid analysis showed lymphocytic exudative effusion, elevated adenosine deaminase (76 IU/L), and plasma cell dyscrasias, indicative of multiple myeloma. Blood tests revealed anemia (Hb 7.5 g/dL) and renal impairment (serum creatinine 2.4 mg/dL). Imaging studies identified multiple lytic lesions in the skull and compression fractures in the thoraco-lumbar spine. Bone marrow aspirate showed 46% plasma cells. The patient was diagnosed with multiple myeloma and initiated on chemotherapy, showing clinical improvement with no recurrence of pleural effusion on follow-up. This case emphasizes the rarity of myelomatous pleural effusion and highlights the importance of early diagnosis and appropriate management. Treatment typically involves chemotherapy, with supportive care to manage symptoms, though the prognosis remains poor in cases of myelomatous pleural effusion.