Using a database comprising 13,266 cytogenetically abnormal neoplasms, the geographic heterogeneity of neoplasia-associated chromosomal abnormalities was investigated by comparing the frequencies of characteristic aberrations in consecutive series of patients with the same diagnosis. Significant frequency differences between geographic areas were found for the aberrations +8, i(17q), +19, and an additional Ph1 chromosome in chronic myeloid leukemia (CML); -5, 5q-, and +8 in acute nonlymphocytic leukemia (ANLL); t(8;21) in ANLL-M2; t(15;17) in ANLL-M3; 5q- and -7 in myelodysplastic syndromes (MDS); t(9;22) and +21 in acute lymphocytic leukemia (ALL); t(14;18) in follicular lymphoma; -8 and -22/22q- in meningioma; and structural abnormalities of 12q in pleomorphic adenoma of the salivary glands (PAS). No geographic incidence variation was detected for -7 and +21 in ANLL; +8 in MDS; 6q- and +8 in ALL; +12 in chronic lymphocytic leukemia; 6q- in non-Hodgkin's lymphoma (NHL); t(8;14) in Burkitt's lymphoma; t(11;22) in Ewing's sarcoma; i(12p) in germ cell tumors; 1p- in neuroblastoma; structural abnormalities of 3q, 8q, and 9p in PAS; or 3p- in renal cell carcinoma. Intraregional frequency similarities between cytogenetically identical abnormalities in related tumor types were also analyzed. No significant correlations were found regarding the incidence of 5q- in ANLL and MDS, 6q- in ALL and NHL, -7 in ANLL and MDS, +8 in ANLL and CML, +8 in ANLL and MDS, +8 in ALL and ANLL, or +21 in ALL and ANLL. The findings indicate that some geographic heterogeneity of tumor-associated aberrations exists both in hematologic neoplasms and in solid tumors.(ABSTRACT TRUNCATED AT 250 WORDS)