Since the number of long-term survivors following radio- and/or chemotherapy for cancer increases, secondary leukemia is now a threatening complication. Several studies already showed that ––5/5q––, ––7/7q–– and ––17 were non-random chromosome changes in secondary leukemia. In this study, a statistical approach was used to better determine the non-randomness of the karyotypic abnormalities and to correlate these aberrations with clinical and demographic parameters. The results showed that there were 16 non-random changes involving chromosomes No. 3, 5, 7, 8, 9, 11, 14, 17 and 21. With the exception of ––5/5q––, the chromosome changes were found to be dependent not only on the type of primary disease and previous therapy, but also on the sex and age of the patients.