Inclusion Criteria:

• MDS with int 2 or high IPSS score eitherRAEB 1 or 2 according to the WHO classification (see appendix 1) or CMML with WBC < 13 109/l RAEB-T according to the FAB classification (see appendix 1) without t(8 ;21), inv 16 or t(16;16) AML secondary to MDS (sAML) with a confirmed MDS phase of at least 2 months with available bone marrow cytogenetics at diagnosis of AML

AND

in CR or PR according to IWG criteria (see appendix 3) after one or two courses of predefined intensive chemotherapy (see page 12) with available cytogenetics at evaluation of response Aged 18 years of age or more Written Informed consent Adequate Contraception, if relevant Negative pregnancy test if relevant. Patients not eligible for the azacitidine confirmatory trial (azacitidine « versus » conventional treatment ») or unwilling to participate to it

Exclusion Criteria:

• AML secondary to myeloproliferative or MDS/MPD WHO subgroups except CMML with WBC< 13 109/l
• Therapy related MDS (after chemo or radiotherapy for a previous neoplasm or immune disorder)
• Patients eligible for allogeneic bone marrow transplantation (with a identified donor)
• Liver and/or kidney failures prohibiting the use of azacitidine. Creatininemia > 1.5 normal value ALAT and ASAT > 3N
• Bilirubin > 2 N, unless due to dyserythropoiesis
• Known hypersensitivity to azacitidine or mannitol
• Other tumor, unstable for the last three years, except in situ uterine carcinoma or basal skin tumor
• Uncontrolled infection,
• WHO Performance status > 2
• Life expectancy less than 3 months