目的：分析19-44 歲國人使用率前五名膳食補充品的使用動機及選用因素。方法：以「2005-2008國民營養健康狀況變遷調查」資料庫中19-44 歲補充品使用者為樣本，共286 位（男108 位，?178位）。結果：除了南部層女性以使用維生素B 群者最多，其他不同居住地區、教育程度、自覺健康狀況、自覺錢足夠性者都是以選擇綜合維生素礦物質比例最高。整體補充品的使用動機以補充營養不均衡者最多；選用因素以親友介紹的比例最高。就個別補充品而言，男、女性使用綜合維生素礦物質及維生素B 群是為了補充營養不均衡；葡萄糖胺/軟骨素預防關節退化。男性吃魚油及蛋白質為了改善體質。女生吃鈣預防骨質疏鬆；吃維生素C 可以養顏美容。男性第1 名選用因素在綜合維他命礦物質及魚油是品牌與口碑，在維生素B 群及葡萄糖胺/軟骨素為親友贈送，在蛋白質是親友介紹。女性選用前五名補充品的因素都以親友介紹者最多。結論：需要深入了解民眾使用補充品的動機及產品選用因素，以擬定有效的管理及教育政策。 Objective: The purpose of this study was to analyze the motivations and determinants associated with the use of dietary supplements by 19-44-year-old Taiwanese people. Furthermore, the use of single supplement of the top five supplements consumed was discussed. Methods：Based on the 2005-2008 Nutrition and Health Survey in Taiwan(NHSIT2005-2008), those 19-44 year-old adults who use dietary supplement were included in this study. Total sample size was 286 (108 males, 178 females). Results：For19-44-year-old adults, In addition to the southern layer women who used vitamin B group, different district of residence, education level, perceived health status, perceived money enough who selected multi-vitamins and minerals as the highest proportion .the top motivation for taking dietary supplements was “improved unbalanced diet”. The top determinant for buying dietary supplements is “a recommendation from relatives and friends”. To individual supplement, both male and female used multivitamin/mineral and vitamin B group for improving unbalanced diet, Glucosamine / chondroitin for preventing arthrosis. Male eat fish oil and protein for improve physical fitness. Female ate calcium to prevent Osteoporosis, eat vitamin C to beauty. Conclusion: In order to achieve an effective education or counseling, health professionals need to have a better understanding of individual motivations and determinants of the use of dietary supplements.