A typical chronic myeloid leukaemia (aCML), which shows both myeloproliferative and myelodysplastic features, is a type of myeloproliferative/myelodysplastic disease as defined by the World Health Organisation (WHO) classification of the myeloid neoplasms. Because of the presence of neutrophilic leukocytosis, aCML may resemble chronic myelogenous leukemia (CML). However, in contrast with CML, aCML does not have the Philadelphia chromosome or the bcr/abl fusion gene. With the continuous karotype analysis of aCML, several changes in the karyotype of aCML have been detected. However, few are recurring and no specific cytogenetic changes have been associated with aCML. Nonspecific cytogenetic abnormalities can be observed in 56%~82% of aCML cases. Although the most frequent abnormalities include trisomy 8 and del (20q), abnormalities involving other chromosomes such as 12, 13, 14, 17, and 19 have also been described. In this report we describe a case of aCML with trisomy 13.