Ascomycetes usually have only one pore in the hyphal septum. This paper reports the first observation of multiperforate septa in lichen fungi using the electron microscope. Multi-perforate septa are reported in Peltigera, Peltula and Hydrothyria. The extra pores probably facilitate intercellular transport of nutrients and water within the thallus. Previous reports of multiperforate septa in other lichen genera using the light microscope need to be verified by electron microscope studies.