This review deals with the most recent findings on the antimalarial, antimycobacterial, and antifungal properties of fatty acids, with particular emphasis on novel marine fatty acids. The first section deals with the most recent and some background literature on what has been the latest developments with respect to fatty acids as antimalarial agents and the importance of enzyme inhibition, in particular the inhibition of the enoyl-ACP reductase (FabI) of Plasmodium falciparum, the principal agent responsible for malaria. This section of the review also emphasizes the latest antimalarial research with the very long-chain Delta5,9 fatty acids from sponges. The second section of the review deals with the recent literature on the antimycobacterial activity of fatty acids and the importance of enzyme inhibition, in particular the inhibition of the enoyl-ACP reductase (InhA) of Mycobacterium tuberculosis for antimycobacterial activity. The inhibitory activities of the Delta5,9 fatty acids against InhA as well as that of the alpha-methoxylated fatty acids are also discussed. The importance of Delta5,9 fatty acids as topoisomerase I inhibitors and its connection to cancer is also reviewed. The last part of the review, the antifungal section, also emphasizes the most recent research with antifungal fatty acids and the importance of enzyme inhibition, in particular N-myristoyltransferase (NMT) inhibition, for antifungal activity. This last section of the review emphasizes the latest research with the alpha-methoxylated fatty acids but the importance of acetylenic fatty acids is also considered.