This paper analyzes the application of the anti-takeover measure poison pill, which is characteristic of American law, while in European and Croatian it is not used as such, but there are some specific measures with which similarities can be observed. The paper is divided into six chapters. The first chapter describes the joint stock company in general, its bodies and the powers of these bodies, which is very important to understand given that the measure of poison pills is exclusively related to joint stock companies. The second chapter discusses the takeover procedure that is necessary for the use of any anti-takeover measure, including the measure that is the subject of this paper. This chapter describes in more detail terms such as acquiring company, target company, takeover bid, etc. It is very important to be familiar with these terms to better understand this paper as a whole. The third chapter discusses anti-takeover measures in general. This section describes the different types of defense measures and outlines in more detail which joint stock company bodies have the authority to adopt them, with a comparison between American, European and Croatian law. The fourth chapter provides an overview of the different types of poison pills with a description of their action and effect on the acquiring company, the target company and the share price. Also, this chapter provides an example of a poison pill in a US joint stock company, and at the very end of this chapter it is described how an acquiring company can defend itself against the devastating economic effects of that measure on their company. The fifth chapter describes why the use of the poison pill is not possible in European and thus in Croatian law. This impossibility is attributed to the principle of equal position of shareholders, the right of first refusal and the regulation of the increase of the share capital of a joint stock company, which are analyzed in more detail in this chapter. Finally, chapter six provides an example of the alternative use of the poison pill in European and Croatian law through approved share capital. This paper provides a complete overview of the use of anti-takeover measures poison pill in the process of taking over a joint stock company and describes its effects that it achieves through its application.