The aim of this cross-sectional study was to determine the influence of test-taking behaviour and risk factors for delayed motor performance in 437 preterm infants (244 males, 193 females; < or = 32 weeks of gestation) at the corrected age of 2 to 3 years (mean 29mo [SD 3.3]). Other mean (SD) sample demographics were: postmenstrual age 29(+5) weeks (1(+5)), range 25(+0)-32(+0); birthweight 1213.7g (331.7), range 468-2350; and days in the neonatal intensive care unit 21.1 (21.3), range 1-165. Children (n=23) with a severe disability were excluded. We assessed motor performance and behaviour during testing with the Motor Scale and the Behaviour Rating Scale (BRS) of the Bayley Scales of Infant Development, 2nd edition (BSID-II). Risk factors were tested against delayed motor performance as the dependent variable in binary logistic regression analysis. Median score on the Motor Scale in terms of the BSID-II Psychomotor Developmental Index (PDI) was 86. 'Delayed' motor performance was observed in 46.5% of the children tested, and behaviour was 'not-optimal' in 31.4%. The Motor Scale and BRS scores were significantly correlated (r(s)=0.62, p<0.01). Risk factors for delayed motor performance were: neonatal convulsions (odds ratio [OR] 4.5; 95% confidence interval [CI] 1.6-12.9), low maternal educational level (OR 3.3; 95% CI 1.7-6.5), male sex (OR 2.8; 95% CI 1.8-4.3), and chronic lung disease (OR 2.1; 95% CI 1.1- 4.1). We conclude that preterm infants are at high risk of delayed motor performance and non-optimal test-taking behaviour.