Chronic myeloid leukemia (CML) is a myeloproliferative neoplasm characterized by the presence of the Philadelphia chromosome, resulting in the constitutive activation of the BCR-ABL1 tyrosine kinase. The advent of tyrosine kinase inhibitors (TKIs) has revolutionized the management of CML, trasforming it from a fatal disease to a chronic condition with excellent long-term outcomes for the majority of patients. The introduction of tyrosine kinase inhibitor (TKI) based treatment for CML has revolutionized the management of this previously fatal disease, achieving sustained disease-control in more than 90% of patients. However, as patients with CML are often required to undergo lifelong TKI therapy to maintain disease control, concerns regarding the long-term safety and tolerability of these agents have emerged. The efficacy of second and third-generation TKIs exceeds the efficacy of imatinib, owing to their potent impact on wild-type BCR-ABL1 and various BCR-ABL1 mutants, along with additional drug targets. Furthermore, TKIs exhibit activity on non-kinase targets (es. oxidoreductase NQO2 for nilotinib and imatinib). The prolonged treatment duration and expanded TKIs repertoire have led the emergence of various unexpected non-hematologic adverse events (AE), notably vascular adverse events (VAEs). Recent evidence indicates a relatively high incidence of severe arterial changes in TKI-treated patients, with VAEs frequency correlating with TKI dosage and treatment duration. However, data elucidating the clinical features of vascular events are lacking. Hormonal alterations have been reported in patients treated with imatinib. The tyrosine-kinase receptors cKIT and PDGF receptors, along with their respective ligands, are expressed in the testis, where they play a role in stimulating testosterone secretion by Leydig cells. Prolonged imatinib use has been associated with reduced testosterone production due to PDGFR and cKit blockade in the testis, potentially leading to gynaecomastia in men. Cardiovascular disease (CVD) remains the leading cause of mortality in the United States, accounting for nearly 40% of all deaths. CVD and ED share a variety of common risk factors, including hypertension, diabetes, dyslipidemia, smoking, obesity, physical inactivity, and metabolic syndrome. Screening and diagnosing ED hold significant potential for secondary prevention of CVD. Despite the estabilished association between ED and CVD, the precise mechanisms driving ED's predictive value for CVD are yet to be fully identified. Early deection and treatment of CVD during the critical time frame in which risk factors can be modified will effectively reduce the occurrence of fatal CV events in male patients with ED. This is a multicentre national, retrospective, prospective, non-interventional study that focuses on male CML patients starting first-line treatment with TKIs between 1 January 2015 and 31 January 2022. All enrolled patients will be involved in both retrospective and prospective evaluations. The retrospective component of the study allows the collection of data on the onset of ED, documented in medical records, that occurred before enrolment. It also includes information from physical examinations and laboratory tests, such as complete blood count, serum biochemistry (including renal and liver function tests, lipid profile and glycosylated haemoglobin), molecular biology for BCR-ABL transcript levels and electrocardiography (ECG), collected retrospectively every six months from enrolment until the documented onset of ED. The prospective evaluation assesses the occurrence of ED in the six months prior to enrolment and during the two-year follow-up period. The primary objective of the study is to assess the incidence of erectile dysfunction (ED) among male patients with chronic myeloid leukaemia (CML) undergoing treatment with tyrosine kinase inhibitors (TKIs), imatinib, dasatinib, nilotinib, bosutinib or ponatinib, focusing in particular on those individuals who report the appearance of associated symptoms after treatment.