Secondary patenting of organic compounds that can undoubtedly be used as active pharmaceutical ingredients (APIs) is discussed. As a rule, such compounds, their synthetic pathways, and potential applications as APIs are patented several years before official authorization to use medicines containing them is obtained. This time lag stimulates attempted illegal secondary patenting of such APIs by new applicants. These attempts can be successful because of the extremely low level of patent review. As a rule, secondary patents contain unconfirmed experimental data and numerous errors, indicating that the applicant and experts lack sufficient professional training. In order to draw the attention of the scientific community to the problem, various aspects of it are discussed below using as examples secondary patents granted for six vitally important drugs used as APIs: abacavir sulfate, darunavir, dasatinib, lenalidomide, apalutamide, and enzalutamide. The appearance of such patents is shown to be inadmissible from scientific, ethical, and legal viewpoints. © 2019, Springer Science+Business Media, LLC, part of Springer Nature.