Patients with high-risk MDS and AML with <30% blasts are today offered treatment with azacitidine, 100 mg/m2 for 5 days every 4th week. In the proposed vaccination protocol, we have chosen to follow this same regimen, but in addition offer vaccination with peptides derived for cancer testis antigens. Patients will be included after completion of 6 courses of azacitidine and a treatment evaluation. If the patient shows response to treatment with azacitidine and the marrow is not hypoplastic, azacitidine treatment will be combined with peptide vaccination to boost the immune reactivity against selected tumor antigens. Patients will be vaccinated with a set of 3 vaccinations, with a vaccination on the 1st day of each azacitidine course, given every 4th week. If treatment is delayed more than 3 weeks the patient is excluded from the protocol. Patients are evaluated for clinical responses after 6 courses of azacitidine treatment combined with vaccination. Patients that are not progressing, will continue azacitidine treatment according to standard schedule, and further vaccinations will be given once every 6th month. Vaccination is continued for up to 2 years after initiation of vaccination or until disease progression.