Spartina alterniflora, the dominant plant species of the tidal salt marshes on the east coast of the United States, contributes significantly to estuarine primary productivity. Energy stored by the plant is released through decomposition as detritus or decomposer biomass. The role of fungi in these transformations has not been elucidated and was investigated in the present study. Dried, dead grass was confined in nylon bags, exposed on a salt marsh and in an adjacent tidal creek in southern Rhode Island, and a quantitative and qualitative study made of the fungi found to be associated with the decomposing grass. Twenty-seven species of fungi were isolated. The average number of fungal colonies/g dry wt. of grass was found to be higher in material exposed on the salt marsh and subjected to immersion only at high tide (2436) than from material immersed in an adjacent creek (1021). The grass lost about 50% dry wt. after 6 months of exposure on the marsh.