Chronic myeloid leukemia (CML) is a hematopoietic stem cell disorder in which the diagnosis is confirmed by detection of a genetic marker: Philadelphia (Ph) chromosome in almost 90% of cases. Some of Ph1 negative patients, nevertheless, test positive for the abnormal gene, or the abnormal protein associated with this chromosome, when more sensitive studies, such as PCR or FISH are used and nowadays the diagnosis of CML is based, not only on cytogenetic, but also on molecular analysis. The better understanding of the CML biology provided by the latest researches requires a deeper knowledge about the epidemiologic data in each geographic area, so the compiling of a National and/or European Registry for CML patients, that represents one of the aims of this study, became a stringent matter in our days; it can offer valuable data concerning the real incidence of this disease in Romania and can provide the basics for establishing long-term budgetary strategies.