Microorganisms associated with decomposing deciduous leaf litter in a woodland stream were examined by scanning electron microscopy. The use of a critical point drying method allowed the preservation of a wide variety of microorganisms as well as the decomposing litter with a minimum of distortion. The micrographs provide evidence that the aquatic hyphomycetes are the major fungal flora present during decomposition. Two distinct groups of these fungi were found during the seasonal cycle with one group occurring only in the summer while the other occurred throughout the rest of the year. The presence of all developmental stages of these organisms in the environment is considered further evidence of their active role in the decomposition of litter.