The author investigated aquatic fungi developing on the seeds of some plants in various types of water bodies of Podlasie Province. The bait method was used to isolate the fungi. Seventy-four aquatic fungal species were found on seeds of three species of plants: Cannabis sativa hemp-seeds 59, Fagopyrum esculentum buckwheat-seeds 55 and on Vicia sativa vetch-seeds 44 in water of four various bodies. The mould species belonged to Blastocladiales (5), Chytridiales (6), Monoblepharidales (1), Hyphochytriales (1), Lagenidiales (5), Leptomitales (4), Peronosporales (14), Saprolegniales (37) and Plasmodiophorales (1). The most common were Achlya americana, Achlya polyandra, Aphanomyces laevis, Pythium rostratum, Saprolegnia ferax and Saprolegnia parasitica. The following phytopathogens were determined: Achlya racemosa, Phytophthora infestans, Pythium butleri, Pythium debaryanum and Pythium myriotylum.