A wide array of partnership exists between algae and fungi. These range from loose commensal association between algae and fungi as in primitive lichens, obligate symbiotic association termed mycophycobioses between the systemic marine fungi and the macroalgae, parasitism where the fungi are pathogens causing disease in the host and saprobic association where fungi grow on senescent to moribund algae. Among these, the fungal parasites are relatively fewer in number than those reported as parasites in terrestrial plans and are limited in their geographical distribution due to their range of host specificity. Fungal pathogens of fresh water phytoplankton play an important role in governing their periodicity in lakes. It is not known whether this holds good for the marine environment too. Fungal pathogens associated with green, brown, red algae and phytoplankton around the coast of India are described here with an emphasis on different kinds of algal-fungal relationships. The observation on seasonal occurrence of a few fungal pathogens, host specificity and changes in physiology of host algae are discussed here