In patients with plasma cell malignancy (multiple myeloma and plasmacytoma), whole-body low-dose computed tomography, magnetic resonance imaging, and 18F-FDG PET/CT are widely applied and suggested by international guidelines to assess the disease extension. Recently, 11C-methionine PET/CT has proven to be promising in those patients compared to other diagnostic techniques. We aimed to review current literature on the state of the art of 11C-methionine PET/CT in patients with plasma cell malignancy. PubMed/MEDLINE database was screened to find articles regarding the role of 11C-methionine PET/CT in plasma cell malignancy. Terms (PET OR positron emission tomography) AND methionine AND myeloma were used. Among 23 studies initially retrieved, 7 (overall 258 patients) were included. In all except two studies, 11C-methionine PET/CT was related to 18F-FDG PET/CT (of whom one also with 11C-4′-thiothymidine PET/CT), one study to 11C-choline PET/CT and one compared multiple myeloma and control patients, both having 11C-methionine scan. Overall, 11C-methionine PET/CT resulted able to detect a higher number of positive patients as well as more bone lesions than 18F-FDG and 11C-choline (detection rate: 75.6–90.7%, 55.0–76.7%, and 73.7%, respectively). A stronger correlation with bone marrow histological results was found for 11C-methionine than for 18F-FDG and 11C-choline PET/CT scans. Although additional studies are needed to validate the role of 11C-methionine PET/CT, it seems to be a safety and effective tool in identification of medullary and extramedullary disease in patients with plasma cell malignancy.