OBJECTIVES:To correct and augment the sample on which a previous study, assessing the applicability of USA WAIS III norms to the UK population, was based. To repeat this study using the modified sample. DESIGN:The WAIS III UK was administered to a supplementary sample, which was used to enhance and correct the original sample, allowing a better match to UK population demographics. METHOD:WAIS III UK scores were processed using USA norms. RESULTS:Distributions of UK IQ, Index, and subtest scores were consistent with USA norms. Means were significantly above USA values and did not show a flat profile. Correlational analysis suggested the presence of an age-related sampling bias, which was then statistically controlled for using analysis of covariance, with age as covariate, to give corrected means. These means, with the exception of two subtests (block design and picture arrangement), did not differ significantly from USA values. CONCLUSION:With a minor proviso concerning the above subtests, it is probable that USA norms can be safely used with the UK population. Future UK samples need to ensure random sampling within demographic categories if sampling bias is to be avoided.