This study describes time trends for very low birth weight multiple births in relation to very low birth weight singletons. Two cohorts of very low birth weight (less than 1250 gm) children recruited between 1983-85 (cohort 1, n = 115) and 1992-94 (cohort 2, n = 144) were compared. The Bayley Scales of Infant Development and a standardized neurologic examination were administered at 2 years corrected age. Neurodevelopmental outcome did not change between cohort 1 and 2 for singletons. For multiple births, mean Mental Developmental Index increased after adjustment for neonatal risk factors [adjusted mean (standard deviation) 81.8 (11.7) to 96.5 (18.6), analysis of covariance P = 0.007]. The prevalence of cerebral palsy decreased, however not significantly [adjusted odds ratio (95% confidence interval) 0.3 (0.1-1.5), P = 0.14]. The proportion of disease-free survival (no cerebral palsy and no developmental delay) increased for multiple births (7-37%, P = 0.002), but not for singletons. In cohort 2, neurodevelopmental outcome of multiple births was similar to that of singletons. The cognitive outcome of very low birth weight multiple births improved, possibly because of changes in perinatal practice. However, neurodevelopmental outcome was similar to that of very low birth weight singletons who were unaffected by changes in neonatal care with high proportions of motor delay and cerebral palsy.