There is evidence of a genetic influence on the decline in cognitive performance of older adults, although the mechanisms responsible are unknown. A group of 767 subjects of the Manchester University Age and Cognitive Performance longitudinal study volunteer group, followed up from 1985 to the present, were genotyped for apolipoprotein E (APOE). The data from this were related to cross-sectional and longitudinal trends in the Heim intelligence test score (AH4-1) using previously reported random-effects models (Neuropsychologia 39 (2001) 532). There were no significant differences in mean scores for presence compared with absence of the APOE4 or APOE2 genotypes (P=0.48 and P=0.51, respectively). This research does not demonstrate a link between intelligence and APOE genotype in older adults.