OBJECTIVES: To understand the infrastructure for HLA-B*5701 screening within the UK and establish the direct cost of correctly screening patients. METHODS: Presence of the HLA-B*5701 allele is associated with predisposition for hypersensitivity to abacavir (KivexaTM, GSK). Some HIV clinicians routinely screen patients for HLA-B*5701 prior to prescribing abacavir. The characteristics and relative costs of available screening methods are therefore integral to the impact of screening on cost-effectiveness of abacavir in practice. Yet this information is poorly understood. No definitive reference cost is available and screening is provided by many laboratory services, to varying specifications and at different cost. Obtaining robust data therefore required a creative approach. Extensive planned research with clinicians and the sales force informed the content and structure of the audit. Interviews were conducted with 25 major HIV centres (currently screening patients for HLA-B*5701 prior to initiation of abacavir therapy), and an advisory board with expert panellists was undertaken during 2006. Methodologies used by different laboratories were explored (with laboratory personnel if necessary) to determine whether screening of sufficient resolution was provided. RESULTS: The audit found three regional networks of laboratories providing genetic screening services to hospitals on a local and national basis. Hospitals routinely accessed different laboratories for different clinical services. Result turnaround times varied from 5 to 14 days, although most laboratories could provide an immediate (2 hour) service if required. The cost of screening varied between 35-90 GBP. Costs were minimised in larger laboratories predominantly through using the latest technologies, batching samples, short transport distances and the use of blood sample aliquots already extracted for other tests. CONCLUSION: UK HIV clinicians have routine access to screening technologies for 4-digit resolution of HLA-B*5701 that are affordable, quality assured and rapid. The impact of this information on the cost effectiveness of abacavir is the subject of ongoing research.