Spanish law 14/2006 introduced the necessary legal platform for scientific use and medical application of preimplantatory genetic diagnosis (PGD) in the Country. Since it was approved, there have been some cases of babies that have been born by artificial reproductive techniques using PGD. The most recent case was the first ″double hope baby″ who was free of beta-thalasemy and a histocompatible donor for his sick older brother. This situation, new in Spain, introduced a new context that confirmed the eugenic consequences of this kind of techniques. This article evaluates PGD starting by a multidisciplinary analysis that covers the technical aspects of PGD and the different arguments which support or detract from it. In summary, the technique involves strong eugenic aspects supported by poor arguments. The need to use valid premises when making legal judgments on biomedical procedures with social consequences, lead us to warn of the consequences of using PGD.