Should parents be obliged to immunise their children against common childhood diseases? Nowadays a significant part of the parents decide not to vaccinate their children because of the far odds to suffer an adverse effect. Some healthcare providers and politicians are claiming to change the immunization calendar into compulsory. I strongly agree with this opinion, because the vaccines’ benefits for society has been clearly demostrated. Kicking off this controversy, I would say that vaccines have been the simplest medical intervention that has saved more lives in history. For example, the vaccine against polio has nearly erradicated the disease in the majority of the world. Furthermore, smallpox has disapeared due to the widespread use of its vaccine. Immmunizations have, with a sometimes ridiculous costs, an enormous impact on public health. However, adverse effects, as in any other mecical treatment, can be seen. It is proved that the incidence of severe deleterious consequences after vaccination, such a nerological o heart involment, are insignificant compared with the huge protection provided. In stark contrast to this irrefutable fact, it exists parents, I believe with a badly undestood “green-attitude”, that reject to vaccinate their children. From my point of view, they are taking advantage from the high prevalence of immunization among the general population. In other words, as the incidence of transmisible diseases protected by vaccines is very low, the odds of their children to get infected with them is also very low. Concluding, vaccination should be mandatory by law regardless of the parent’s opinion.