We investigated the effects of folate-enriched egg yolk powder on folate and homocysteine levels in plasma and liver of rats fed the folate- and choline-deficient diet to determine bioavailability in vivo. Three-wk-old Wistar rats were fed (1) the pteroylglutamate (PteGlu), (2) the choline, (3) the PteGlu and choline, (4) the folate-enriched egg yolk powder diet for 4 wk after having been fed the folate- and choline-deficient diet. The hepatic folate level in the folate-enriched egg yolk powder group was significantly higher than that in the folate- and choline-deficient or the control groups. The homocysteine concentration in plasma and liver of the folate-enriched egg yolk powder group was significantly lower than that of the folate- and choline-deficient or the PteGlu groups. The S-adenosyl-methionine (SAM)/S-adenosyl-homocysteine (SAH) ratio in the folate-enriched egg yolk powder group was significantly higher than that in the folate- and choline-deficient group. These effects were similar in the PteGlu and choline, but not the PteGlu or the choline groups. These data suggest that the intake of folate-enriched eggs, as well as of both folate and choline, induced the beneficial effects on folate and homocysteine metabolism. Thus, folate-enriched eggs could be used as beneficial source of folate with a high bioavailability.