Plasma cell leukemia (PCL) is a rare malignant plasma cell neoplasm with aggressive clinical progression, minimal response to therapy and unfavorable prognosis. Concomitant new coronavirus infection COVID-19 and its complications significantly worsen prognosis in patients with PCL. Currently, approaches to PCL therapy are not finalized, and regimens developed for multiple myeloma are used. In PCL, the most common clinical symptoms are renal failure and hypercalcinemia which are frequently observed in multiple myeloma. Therefore, use of proteasome inhibitor (bortezomib) with proven effectiveness in multiple myeloma, is justified. A clinical observation of a 64-year-old female patient who was hospitalized in poor physical condition with the new coronavirus infection COVID-19 is presented. During hospitalization, debut of PCL was suspected, and as soon as possible after diagnosis confirmation using vital indications, antitumor drug therapy was started with positive effect.