In the master thesis »Is predatory pricing in digital platform economy a rational business strategy?« my goal is to conduct a research relating to rationality of predatory pricing in digital platform markets. Research is based on legal theory and jurisprudence in United States and European Union. First, I introduced the economic theory of digital platforms, which is followed by definition and theory of business strategy. In third part, I present the historical development of jurisprudence in EU and US regarding the doctrine of predatory pricing and moreover, of predatory pricing in digital platform economy. In the analysis of European jurisprudence I have analyzed the following cases AKZO, Tetra Pak, Wanadoo (France Telekom), Post Danmark I and Intel. The Court of Justice of the European Union has throughout the history turned its goal from market integration of the internal market towards consumer welfare. The assessment is thus, based on a more economic approach. In the analysis of the U.S. Supreme Court jurisprudence I had examined the following cases Standard Oil, Utah Pie, Matsushita v. Zenith and Brooke Group. The Court developed the antitrust doctrine by citing Chicago School scholars. A more economic approach is relevant in the cases concerning predatory pricing in digital platforms because it results in better final decisions. In the last fourth part, I have analyzed the rationality of predatory pricing in digital platform economy and I have also presented a case study regarding business pricing strategy done by Amazon. At the end, I have concluded that predatory pricing in the market of digital platforms could be a rational business strategy.