ABSTRACT Myelodysplastic syndrome with deletion of chromosome 5q (5q-syndrome) has a favorable prognosis and a low risk of transformation to acute myeloid leukemia, when treated with lenalidomide. Azacitidine leads to complete remission even as second-line therapy and in patients with clonal evolution. We report a 70 years old female without previous exposure to myelotoxic drugs, presenting with three weeks with fatigue and dyspnea. She had anemia with normal white blood cell and platelet count. Bone marrow biopsy showed 50% cellularity and the karyotype analysis revealed a (5) (q33q34) deletion in 22% of the metaphases. A diagnosis of 5q-syndrome with low risk calculated using the Revised International Prognostic Scoring System (IPSS-R), was made. Since lenalidomide was not affordable, thalidomide 100 mg/day was initiated, achieving transfusion independence for three years. Afterwards, she developed pancytopenia and a bone marrow biopsy showed erythroid and megakaryocyte dysplasia with a complex karyotype, which worsened prognosis (IPSS-R of five points). Therefore, azacitidine (by donation) was administered. She achieved complete remission with a normal karyotype and completed 12 cycles of treatment. Thereafter, she relapsed and received only supportive care for a year. She suffered an ischemic stroke and died two weeks later.