Cytogenetic studies were performed in nine patients with non-Hodgkin's lymphoma; four were lymphoblastic lymphoma, three Burkitt's-type and two diffuse lymphomas with mixed small and large cell. All cases showed pseudodiploid or hyperdiploid mode and, moreover, four cases had metaphases with a normal karyotype. All patients showed clonal chromosomal abnormalities, except one (lymphoblastic T-lymphoma). The translocations t (8;14) (q24;q32) and t (8;22) (q24;q11) were the abnormalities found in Burkitt's lymphoma. The translocation t (14;18) (q32;q21) was found in one case, of lymphoblastic type. In the other tumours, the chromosomes involved in the different aberrations were: #1, #3, #7, #8, #9, #14 and #17. We attempted to correlate the cytogenetic findings with histology and prognosis.