To investigate ten year trends in folate status in Taiwanese aged >=19 yrs by three Nutrition and Health Survey in Taiwan (NAHSIT) in 1993-1996, 1999-2000 and 2005-2008. Women had higher blood folate levels than men in all three surveys. The prevalence of folate deficiency (5.2% <3 ng/mL) and insufficiency (34.1% <=6 ng/mL) in men was highest in 2005-2008. Adults aged 19-30 yrs had the lowest blood levels and the highest prevalence of deficiency (8.1% in men; 3.5% in women) and insufficiency (48.6% in men; 25% in women) as compared to other age groups in 2005-2008. Folate insufficiency rate in those aged 31-44 yrs was twice as high in men and three times as high in women in 2005-2008 compared to 1993-1996. In the elderly, folate insufficiency rate (28%) in 2005-2008 was not higher than that of 1993-1996, although it was higher than that found in 1999-2000 (18.4%). Men aged >=80 yrs had the poorest folate status in 2005-2008, and men were twice as likely to have inadequate status as women. Plasma homocysteine (Hcy) levels were higher in older men than older women in both surveys. The elderly had significantly higher plasma tHcy in 2005-2008 compared to the 1999-2000 survey. Dark green vegetables and fruit intake frequency in young adults (19-30 yrs) was the lowest among all age groups. This study suggests that folate status in Taiwan has not improved during the past fifteen years, and has worsened in the young population.