Vitamins maintain growth and development in hu-mans, animals, and plants. Because plants serve as essential producers of vitamins, increasing the vi-tamin contents in plants has become a goal of crop breeding worldwide. Here, we begin with a summary of the functions of vitamins. We then review the achievements to date in elucidating the molecular mechanisms underlying how vitamins are synthe-sized, transported, and regulated in plants. We also stress the exploration of variation in vitamins by the use of forward genetic approaches, such as quanti-tative trait locus mapping and genome-wide associ-ation studies. Overall, we conclude that exploring the diversity of vitamins could provide new insights into plant metabolism and crop breeding.