To evaluate the role and application of flow cytometry in the diagnosis of non-Hodgkin lymphoma (NHL).Fresh cell samples from 40 cases of lymphoproliferative disorders were obtained by fine needle aspiration or excisional biopsies. Multiparameter flow cytometry was used to study the surface antigens of lymphoid cells. The immunophenotyping results were also correlated with morphologic features seen in the cytology preparations.Of the 40 cases with histologic diagnosis of NHL, 37 cases (92.5%) had the lymphoma diagnosis confirmed by this method. The concordance rate for the 20 cases of B-cell NHL was 100%. As for the 17 cases with histologic diagnosis of T-cell NHL, 12 cases (66.7%) were correctly diagnosed as T-cell NHL using flow cytometry...