summary The aim of this study was to assess the performance of HIV screening kits introduced over a 12-year period. HIV kits used by the National Blood Service (NBS) were assessed in the context of other HIV kits employed by diagnostic and reference laboratories. Thirty-three HIV screening kits were assessed and 13 had the potential to be used by the NBS. Specimens applied to NBS evaluations included 2000 HIV-negative specimens collected from blood donors, 200 HIV-positive specimens and 21 seroconversion panels, with larger numbers applied to the latter two categories prior to implementation of Communauté Européennes (CE) marking. The 33 HIV kits gave repeat reactive rates, based on HIV-negative specimens, of between 0% and 0·8% (and between 0% and 0·2% for kits relevant to the NBS). When examined for diagnostic sensitivity, the 33 kits gave sensitivities between 99·78% and 100%. Kits relevant to NBS gave sensitivities of 100% except one kit, which failed to detect one anti-HIV-2-positive specimen. Twenty-six kits were compared for detection of primary HIV infection. Of these, the 10 combined HIV antigen/antibody kits examined were more sensitive than other formats and have been exclusively adopted by NBS where operational considerations allow. Their added seroconversion sensitivity makes them the screening method of choice for populations at increased risk, e.g. in sexually transmitted infection (STI) clinics. The regular review of evaluation results has demonstrated a continuing improvement over time in the performance of HIV screening kits and contributed to advances in blood safety.