The subject of the considerations in this article is the crime of forgery of documents, as defined in Art. 270 of the applicable criminal law in the context of an act of illegal border crossing. In accordance with applicable law, the so-called simple illegal border crossing is an offense specified in Art. 49a of the Code of Petty Offenses, while Art. 264 § 2 of the CC applies when the border is crossed contrary to the provisions in cooperation with other persons or with the use of violence, threats, deception, i.e., inter alia, in a situation where false documents are used to cross the border contrary to the law. They can also be a tool enabling the performance of the act specified in § 3 of the aforementioned art. 264 of the Penal Code, which penalizes the activity consisting in organizing the crossing of the border by other persons against the provisions of the law. The main purpose of the study is to draw attention to the crime of document forgery as a practice that allows for other legally prohibited acts. In this light, the thesis was formulated according to which forged documents are in many cases a tool used by foreigners to illegally cross the borders of the Republic of Poland, and thus the Schengen/European Union area. The thesis was confirmed in studies conducted on the basis of statistical data of the Border Guard Headquarters from 2016–2022. Their analysis is presented in the article