Synthesis of defensive pathogenesis-related (PR) proteins in plants is induced by biotic and abiotic stress. The family of plant PR proteins is divided into 17 classes differing in their structural and functional properties. Two representative classes of plant PR protein family are Bet v 1 (PR-10) homologs and lipid transfer proteins (LTP, PR-14). The ability of PR-10 and PR-14 to bind and transfer lipids and other hydrophobic ligands contributes to a wide range of plant metabolic processes. Although these proteins are not homologous, they have similar spatial structures containing a hydrophobic cavity, which is capable of accommodating and retaining various molecules, including lipids. The present review focuses on structural features of Bet v 1 homologs and LTP, possible ways of binding and transfer of lipids, and assumed biological functions associated with the delivery of building and signaling hydrophobic molecules in plants, as well as participation of these proteins and their lipid ligands in the development of allergic reactions.