CNS involvement in AML is a rare event, poorly detailed in literature. Few data are available in pediatric cases, and less frequent in adult cases. Predisposing factors for AML adult patients with CNS involvement include young age, higher level of lactate dehydrogenase and white blood cells (WBC) counts at diagnosis, FAB M4 and M5 morphology, chromosome 16 inversion and chromosome 11 abnormality. No consensus exists regarding the treatment of AML patients with CNS involvement. Protocols used for AML treatment are largely based on high doses of cytarabine, which penetrate the blood brain barrier. On the contrary of acute lymphoid leukemia (ALL), prophylaxis with intrathecal chemotherapy is not routinely used in AML. Roudoski et al. showed that, when lumbar puncture (LP) was performed in 1,370 patients, only if clinically indicated, CNS disease was detected in 45 (3.3%) patients. Another 42 patients underwent routine LP as part of an investigational protocol, and in 8 (19%) CNS disease was detected (P\<0.0001). Risk factors included high LDH, African-American ethnicity, and young age. Patients receiving high-dose cytarabine and those that did not had similar rates of CNS involvement. Disease free survival (DFS) and overall survival were shorter in patients with CNS involvement. Treatment in case of CNS involvement is not well established; the potential acute and long-term complications associated with cranial irradiation often limit its use. Prognosis remains poor also with high doses of cytarabine and/or therapeutic intrathecal chemotherapy. Castagnola et al. reported showed the outcome of 9 patients woth CNS+ AML: NSL was treated as follows: 4 patients received combined systemic HD Ara-C, cranial radiation therapy and intrathecal (IT) methotrexate (MTX); a second group of 4 patients was treated with HD Ara-C, IT MTX without cranial irradiation; HD Ara-C alone was administered in one patient. All patients of the first group and 2 patients of the second who achieved a complete remission (CR) had a median survival of 10 months after CNS involvement, while for the non-remitters it was 2 months. The unique durable response was observed after allogeneic bone marrow transplantation. Sanders et al. reported that craniospinal irradiation with or without intrathecal chemotherapy appears to be effective at eliminating leukemia in the craniospinal axis. However, the eradication of disease in the CNS was not found to be effective at preventing disease recurrence in the bone marrow, and despite improved control of disease in the CNS, adult patients with a CNS recurrence still had a poor prognosis. Furthermore, the rapidly fatal course of disease prevented an assessment of the durability of CNS response to irradiation. Aoki et al reported that allogeneic haematopoietic stem cell transplantation (HSCT) might improve outcomes for CNS+AML and Bar et al, showed that presence of CNS pre-HCT had no independent influence on post transplant outcome, which was primarily influenced by status of systemic disease at time of HCT. Due to the rarity of the disease we want to collect the data about CNS involvement, either at diagnosis or along the course of the disease, in AML patients already registered in previous GIMEMA Studies, trying to identify incidence, prognosis, prognostic factors and the best adequate treatment.