A high total homocysteine (tHcy) level during pregnancy is a risk factor for adverse perinatal outcomes, such as fetal growth restriction and preeclampsia. Caffeine is assumed to increase tHcy levels by acting as a vitamin B6 antagonist. The objective of this study was to examine a relationship between circulating tHcy levels and dietary caffeine and vitamin B6 intakes in pregnant Japanese women. A total of 321 healthy women with singleton pregnancies were recruited in metropolitan Tokyo, from June to December 2008, resulting in the ﬁnal number included in the study as 254. Dietary caffeine intakes did not correlate with plasma tHcy levels. When we analyzed the data according to caffeinated beverages, caffeinated tea consumption was positively associated with plasma tHcy levels only among the women with a high intake of vitamin B6, after controlling for confounding factors (P= 0.029). No correlation between coffee consumption and plasma tHcy levels was found. Pregnant Japanese women might need to cut down the consumption of caffeinated tea as well as take sufﬁcient vitamin B6 in order to prevent the tHcy levels from increasing.