Livestock manure may contain pathogenic organisms which pose a risk to the health of animals or humans if the manure is not adequately treated or disposed of. One possible treatment method is composting. However to ensure that pathogen destruction occurs, temperatures need to be sufficiently high throughout the heap to ensure that pathogens are inactivated. The temperature required to inactivate a marker organism, Escherichia coli 11943, has been investigated, and found to depend on substrate composition, moisture content and duration of incubation. Results show that temperatures in excess of 55 degreesC for 2 h are required for inactivation, Data are presented showing the levels of faecal coliforms in compost heaps where temperatures did not rise above mesophilic levels (35 degreesC where samples were taken).