Twelve cultures of Hyphomycetes capable of growth upon the ethane component of natural gas were isolated from raw sewage by a continuous enrichment technique. In addition, all isolates also grew on propane and n-butane but not methane. These cultures are described and their taxonomic position discussed. Four were tentatively placed in Graphium; three were identified as Phialophora jeanselmei (Langeron) Emmons; the remaining five are similar to Acremonium sensu Gams.