More than two decades have past since the recognition of non-Hodgkin's lymphomas (NHLs) as neoplasms of the immune system. During that time, a vast literature and knowledge base regarding the immunophenotypic and functional characteristics of neoplastic lymphocytes has been developed. Despite the accumulated wealth of knowledge, there remains no consensus as to the exact role of immunotypic and genotypic ancillary procedures in the evaluation of a lymph node biopsy. We review selected literature in this regard and provide an overview of the role of multicolor flow cytometry in establishing the diagnosis of specific NHL and related disorders.