There are already several countries that have accepted marijuana as a soft drug, separating it from more dangerous ones. Yarious therapeutic properties have even been attributed to its use. Others, however, think that its use should be prohibited due to the mental interference and behavioral changes produced either by its occasional use as well as the permanent mental damage linked to chronic marijuana use. In order to clarify this divergence of opinions, the scientific literature is reviewed. It is concluded that there is a serious risk, especially for teenagers, associated to chronic marijuana use due to the presence of more frequent psychotic and schizophrenic episodes, which can be permanent, while consumption during pregnancy results in brain damage to the fetus, similar to fetal alcohol syndrome. Scientific research also indicated that smoking marijuana produces an even more severe bronchial damage than tobacco, with risk of lung cancer. In conclusion, the notion that marijuana is a risk-free soft drug is a serious mistake, based on the available conclusive scientific research that shows the opposite.