['This study explored the association between three measures of working memory ability and genetic variation in a range of catecholamine genes in a sample of children with ADHD.', 'One hundred and eighteen children with ADHD performed three working memory measures taken from the CANTAB battery (Spatial Span, Delayed-match-to-sample, and Spatial Working Memory). Associations between performance on working memory measures and allelic variation in catecholamine genes (including those for the noradrenaline transporter [NET1], the dopamine D4 and D2 receptor genes [DRD4; DRD2], the gene encoding dopamine beta hydroxylase [DBH] and catechol-O-methyl transferase [COMT]) were investigated using regression models that controlled for age, IQ, gender and medication status on the day of test.', 'Significant associations were found between performance on the delayed-match-to-sample task and COMT genotype. More specifically, val/val homozygotes produced significantly more errors than did children who carried a least one met allele. There were no further associations between allelic variants and performance across the other working memory tasks.'] Is the COMT Val158 allele associated with impaired delayed-match-to-sample performance in ADHD?