This article poses a research question of the significance and necessity of guerrilla marketing in small and medium-sized enterprises. The thesis is that guerrilla marketing is vital and essential for the successful development of medium-sized and small enterprises. Guerrilla marketing in medium-sized and small business today is becoming increasingly necessary. It is the key to the success of medium-sized and small enterprises. With small monetary investments guerrilla marketing facilitates the success and development of medium-sized and small enterprises. It requires entrepreneurs to invest their time, know-how, adaptability and imagination. All these features need to replace the money that medium-sized and small business do not have at their disposal in sufficient amounts to compete with large companies that can invest in classical marketing. The factor of surprise and shock should initially attract the interest of buyers for a product or service and after that a true guerrilla needs to undertake an entire series of activities in order to retain the interest of buyers and to attract new buyers. There is a series of activities that guerrillas need to undertake so that their business can be more successful. There are also many issues that entrepreneurs need to take into account, as omitting them could cause damage to their business or profit. These mostly relate to features of guerrilla companies and their attitudes. At the same time it is important for entrepreneurs to be aware of consumer habits as this will facilitate impacting their decision to buy a product or service. New technology and the Internet are a useful tool for guerillas because they provide a broad spectrum of cheap or free advertising which requires creativity to attract buyers. Medium-sized and small businesses need to be aware of the main components of guerrilla marketing so that they can progress surely and easily in their own business.