Although spore release patterns are known for many important fungal pathogens of higher plants, little is known about them in agarics. Haard and Kramer (1970) and Rockett and Kramer (1974) found most of the agarics and boletes tested to have circadian rhythms of spore discharge, with maxima at night and minima in the daytime. Exceptions were young basidiocarps of Collybia, Lactarius, and Boletus, which, after being desiccated at an early stage of development, would revive and shed spores immediately after a rain. The property of revival, in the sense of regaining form and shedding spores after rewetting, has been important in the taxonomy of the Tricholomataceae, particularly in the separation of Marasmius from Mycena and Collbia. Since at the time of the present study I was preparing a taxonomic treatment of Marasmius in the northeastern and north central United States, I was interested in documenting the extent of revival in at least one species of this genus. The present study examines spore discharge patterns in Marasmius rotula, a species commonly recognized as having reviving basidiocarps. Parameters affecting spore discharge in other fungi are investigated as they apply to this species. Revival as it occurs in Marasmius rotula is compared with that reported for other genera.