Statistics have been compiled on active and closed landfills in Sweden, numbering about 300 and 4000 respectively. Mechanisms and potentials for methane production are briefly reviewed, and criteria are developed for selecting landfills that should be equipped with methane recovery plants. The following criteria are suggested: Landfills should have methane recovery systems if, - they receive municipal waste from at least 10,000 persons or more than 3,000 tons/year. Recovery should begin within 5 years after deposition and continue for at least 25 years., - they receive large quantities of organic waste from industry, or sludge that has not been treated biologically. Exceptions can be made if proved that gas recovery is not possible., - closed landfills over 200,000 m(sup 3). Exceptions as above, and for landfills closed before 1965. The limit, where recovery is not considered to be possible, may be: less than 150 kW and a net cost of 0.3-0.4 SEK/kWh (about 0.04-0.05 USD/kWh). 23 refs, 42 figs