We studied the association between plasma total homocysteine concentrations and the occurrence of stroke in newborn infants (n = 24). Newborn infants with stroke had significantly higher mean total homocysteine concentrations compared with 94 healthy newborn infants (9.3 vs 7.4 micromol/L). The odds ratio for neonatal stroke was 3.95 (95" CI 1.53-10.16) at the 80" cutoff level.