Today's technological level enables the computer system to be connected to the network as well as their global connectivity into a unique communication-information system - the Internet. Technological development of the internet has enabled a great deal of misuse due to the lack of or insufficient legal regulation in the field of computer crime. The notion of the Internet is closely related to the term information system. The information system is a set of clearly defined rules, practical experience and methods of work where people or groups of people need to work on entering data into a computer that will process information so as to provide all the specifications, which will enable individuals to decide in specific situations. Since at present level of development it is not possible to achieve absolute security of the information system, it is necessary to provide absolute and effective protection if abuses occur. The issues of computer crime are issues whose occurrence is increasingly common in modern society. Computer criminality is created and developed in the same way in all parts of the world. It is publicly written and spoken about, and the results of its prevention are practically negligible. Today, this is no longer the case because more and more countries have described criminal offenses arising from the use of modern information technology technologies in their own national legislation. Through the 2004 Act on Amendments to the Criminal Code, the Republic of Croatia prescribed a number of criminal offenses described in the Convention on Cybercrime.