Objectives: To establish a surveillance programme for HIV drug resistance within the UK covering the years Zrolm 1998 to 2000, following the introduction of triple combination antiretroviral therapy. Methods: Sentinel sites included large, medium sized and small clinical centres. Data were analysed until December 2000. Results: Of nearly 300 samples tested, results from 91, 92 and 92 patients, respectively in 1998, 1999 and 2000, who were receiving HIV therapy with a viral load >2000 copies/mL, the majority had viruses with some degree of drug resistance. Overall, the presence of any resistance increased between 1998 and 1999, and fell again in 2000 (69% versus 88% versus 55%). However, major differences were observed between drug classes, such that non-nucleoside analogue reverse transcriptase inhibitor (NNRTI) resistance rose dramatically over the period studied. We show that this correlated with increased NNRTI prescribing. Furthermore, an overall increase in prevalence of viruses with resistance to one or more drugs within all three available classes was observed. A higher prevalence of drug resistance was observed in patientsfrom smaller clinical centres. Conclusions: This is the first such sentinel surveillance dataset from the UK, and is unique in correlating these data with national antiretroviral prescribing patterns. Our findings are relevant to the increased transmission of HIV drug resistance observed over this period.