Introduction: Monoclonal gammopathies are a group of disorders associated with monoclonal proliferation of plasma cells that produces a monoclonal protein. To describe the epidemiological and immunochemical characteristics of monoclonal gammopathies diagnosed during a nineteen-year period in a Moroccan teaching hospital was the main objective of this study. Methods: This study was performed from January 2000 to August 2019. It was a retrospective study that included of 545 Moroccan patients with monoclonal gammopathy. Results: The patients who participated in the study, 374 (68.6%) were male and 171(31.4%) were female, with a mean ±SD age of 62.24±13.14 years. The most frequent reasons for admission were bone pain (41,60%), renal failure (19.08%), alteration of the general condition (12.21%) and anemia (10.69). Plasma cell proliferative disorders in our study were as follow, multiple myeloma (MM) (45.65%), Monoclonal gammopathies of undetermined significance (MGUS) (39.05%), Waldenstrom’s macroglobulinemia(5.58%), Lymphoma (2.27%+1.2%), Chronic Lymphocytic Leukemia (2.48%), Plasma cell leukemia (1.86%), Plasmacytoma (0.62%), POEMS syndrome (0.41%), and Amyloidosis (0.84%). The most frequent isotypes in MM were the IgGκ (62) 36.5%, IgGλ(52)30.6%, IgAκ(27)15.9% and the IgAλ (19)11.2%. It is also worthy of note, that Free light chain MM represents 20% of all cases of MM. Conclusions: This is the largest Moroccan cohort, it included 545 patients. The results of this study point to the need for an early diagnosis of monoclonal gammopathies in the Moroccan population