A study was undertaken to assess the performance of laboratories participating in the UK unlinked anonymised neonatal screening programme for the detection of HIV antibody. A coded panel of 100 contrived dried blood spots prepared form well characterised anti-HIV-1 and anti-HIV-2 positive sera and an anti-HIV negative serum was distributed to eight testing centres. Fifty-one out of 52 anti-HIV-1 positive samples were identified by all eight laboratories: five laboratories identified all 52 specimens. Only one laboratory detected all four anti-HIV-2 positive spots. None of the laboratories reported a seronegative spot as reactive. The sensitivity of anonymised neonatal anti-HIV-1 screening was deemed satisfactory in all participating laboratories but the margin of sensitivity was insufficient to allow pooling of dried blood spot eluates before testing. Technical modifications would be necessary to increase sensitivity for anti-HIV-2 were HIV-2 infection to be reported more frequently in the UK. Performance assessment of the screening programme should be repeated at regular intervals.