OBJECTIVES: State funded healthcare systems, such as the UK, tend to be cautious with the diffusion of new drugs for fear of financial pressures. One way of controlling diffusion, while maximising the benefits for patients, is to set up an outcome guarantee. This presentation describes a case study using lipid lowering drugs, recently completed. METHODS: The key stakeholders were identified and each declared their interest on an agreed matrix. This formed the basis of an outcome guarantee contract. Near patient testing and audit nurses were used to identify at risk patients and enter them into an agreed care pathway. Patients were given lifestyle advice, re-tested and monitored every 3 months throughout the 18 months of the project. Results of treatment with lipid lowering drugs were measured against their claimed benefits and adjusted for concordance. If the drug under-performed, according to agreed criteria, the pharmaceutical company agreed to refund the cost of those drugs. RESULTS: The concept was readily accepted by the stakeholders. Two thousand at risk patients were identified from 1 primary care trust, of which 1400 were eligible to enter the outcome guarantee. Six hundred patients to date have completed the project. Final results are due in July. Of those who have completed the project, the majority have reached target level and no refund has been due. A qualitative evaluation of the stakeholders is currently under way and will be reporting in August 2002. CONCLUSIONS: An outcome guarantee is an acceptable way for a nationally funded health service to partner a pharmaceutical company for optimal diffusion of drugs likely to benefit a patient population. The model has potential for replication in other therapeutic areas and other healthcare systems.