The persistence and degradation of heptachlor varied considerably by location in tests in 5 areas of the United States. Relatively high values for 1-hydroxy-chlordene, representing approximately 60% of the insecticide in the soil, were obtained for extracts of a Quincy loamy fine sand from Oregon. Significant amounts of 1-hydroxy-chlordene were found in the extracts of Lake land sand from Florida. Generally, heptachlor epoxide represented only a small fraction of the insecticide present in the soils.