Plasma cells (PC) are the terminally differentiated effector cells of the B-cell lineage. The aim of this review is to integrate relevant data on the phenotype of plasma cells, including reactive and malignant PC. The current World Health Organisation classification of lymphoid neoplasm is based on correlation of their morphologic, histologic, immunophenotypic, genetic and clinical features. The extensive application of imunohistochemistry is necessary in diagnosis of plasma cell neoplasm, but also in determining prognosis as well as in evaluating residual/ relapsing disease. This review focuses on immunohistochemical analysis non-neoplastic and neoplastic plasma cell proliferation in facilitating the diagnosis and highlights the recent advances that have been made with regard to their stratifying.