Background: Multiple myeloma is a disease of the elderly. However, 40% of patients are diagnosed before 65 years old. Outcomes regarding age as a prognostic factor in MM are heterogeneous. Method: We retrospectively analyzed clinical characteristics, response to treatment and survival of 282 patients with active newly-diagnosed multiple myeloma, comparing results between patients younger and older than 65 years. Main results: The frequency of multiple myeloma in those younger than 66 years was 53.2%. Younger patients presented with a more aggressive disease, more advanced Durie-Salmon stage (85.3% vs 73.5%; p=0.013), extramedullary disease (12.7% vs 0%; p<0.001), osteolytic lesions (78.7% vs 57.6%; p<0.001) and bone plasmacytoma (25.3% vs 11.4%; p=0.003). In spite of this, the overall response rate was similar between groups (80.6% vs 81.4%; p=0.866). The overall survival was significantly longer in young patients (median, 65 months vs 41 months; p=0.001) and higher in those who received autologous hematopoietic stem cell transplantation. The main cause of death was disease progression in both groups. Multivariable analysis revealed that creatinine ≥2mg/dl, extramedullary disease, ≤very good partial remission and non-autologous hematopoietic stem cell transplantation are independent risk factors for shorter survival. Conclusion: Although multiple myeloma patients younger than 66 years of age have an aggressive presentation, this did not translate into an inferior overall survival, particularly in those undergoing autologous hematopoietic stem cell transplantation.