Financing through Initial public offering (IPO) is one of the ways of raising funds for the operational or development needs of the company. An IPO is the first public offering of a company's shares to potential investors and it takes place on the primary capital market, that is the stock exchange. The subject of the final thesis refers to the analysis of initial public offers on the Zagreb Stock Exchange. The objective of this paper was to analyze all relevant facts about the initial public offering, to identify the motives of companies to financing through IPOs and to analyze the efficiency of the five largest IPOs conducted on the Zagreb Stock Exchange by amount of capital raised. The following methods were used in the research: analysis, synthesis, comparison, compilation, as well as selected tools of business and financial analysis. Secondary data sources were primarly used, such as scientific and professional literature, as well as publicly available statistical databases and data from the official website of the Zagreb Stock Exchange. The analysis of the effectiveness for five largest IPOs on the Zagreb Stock Exchange showed underpricing in three of the five analyzed cases. In the remaining two cases that were analyzed, the stock price was set more precisely during the IPO, which resulted in a more efficient collection of the required capital.