The UK market for leachate treatment technology has been characterized recently by the entry of companies bringing to it heavily-marketed specific systems. Whilst derived from other effluent treatment and industries, they often have no track record of application to landfill leachates. Knowledgeable and independent advice for the selection of appropriate technologies at specific sites has been in short supply. A common scenario has been the release of tender documents asking for ‘design and build’ solutions, which have resulted in submission of schemes based on a whole range of systems (for example: aerobic biological; anaerobic; reverse osmosis; ammonia stripping, etc.), such that the client commissioning the scheme has been unable to make a well-informed choice between compatible technologies. In several instances, systems have been adopted which have not provided complete solutions. The most widespread experiences of successful leachate treatment in the UK have involved the use of biological processes in aerated lagoons or tanks. The paper describes a wide range of full-scale, aerobic biological leachate treatment systems, selected from several in the UK and abroad. These range from relatively simple aerated lagoons, designed to provide pretreatment before the discharge of effluent into the sewerage system for final treatment, to sophisticated schemes where surface water discharge consents demand that rainbow trout shall be able to survive in undiluted effluent. Case studies give detailed data for removal of specific contaminants at each plant. Reference to very detailed information in other published papers is provided, and analytical results for influent leachates and discharged effluents are provided, together with detailed operating data. The paper demonstrates that the on-site treatment of landfill leachate using aerobic biological techniques, to whatever standard required, is established technology in the UK.