The main purpose of this graduate thesis is to point out the opportunities and benefits of using the guerrilla marketing strategy in Croatian advertising agencies. Guerrilla marketing is an innovative and modern tool that marks the approach to finding new, alternative approaches and ways to customers. According to the concept of marketing, consumer needs are in the focus, therefore, in order to achieve the goals of the organization it is necessary to spot the needs and desires of consumers that are on today's market very demanding. That is why organizations need to attract the attention of potential customers or clients in an interesting and shocking way. In this case, guerrilla marketing can be online and offline and the features are: inexpensive, shocking, expanding rapidly and unconventional. The paper deals with guerrilla marketing and all the notions related to it, with special reference to Croatian advertising agencies. Under the influence of the Internet, especially social networks, guerrilla marketing is an excellent way to build a company's image, but also to turn attention to its products. Empirical research is based on a qualitative research of attitudes of employees on the occasional sample in nine agencies that are HURA members with the help of the open question questionnaires. Analysis of the hypertext content (websites) regarding guerrilla marketing has been conducted on all HURA member agencies. It was concluded that advertising agencies are familiar with the term guerrilla marketing and that usage of guerrilla marketing in their business and campaigns is increasing. The agencies have noted the advantages of a different approach in marketing and advertising business, which is led by guerrilla marketing.