The vertical distribution of microbial adenosine triphosphate (ATP) was determined seasonally for sediments of the salt marsh at Sapelo Island, Georgia. Two study areas were chosen representing major differences in productivity of the marsh grass,Spartina alterniflora. The streamside zone represented an area of greater production ofS. alterniflorathan did the high marsh zone. In addition, differences in other features were noted.In all cases the concentration of ATP was greatest in the surface 1 cm and decreased with increasing depth. ATP varied seasonally in both regions. A comparison was made of the sediment organic carbon and total nitrogen within the sediments and the calculated carbon and nitrogen associated with the microbial community. The contribution of these elements within the microbial community is at most a few percent of the total pools. The surface sediment ATP values reported here are within the range of those for water-logged sediments from various diverse environments.