Abstract: The invention describes the riboflavin biosynthesis gene and gene products from yeast. Vectors and recombinant preparation processes for riboflavin are furthermore described. Specifically, the invention relates to the genes for riboflavin biosynthesis in yeast, the proteins encoded therewith and genetic engineering process for the preparation of riboflavin using these genes and gene products. Accordingly, six genes (rib genes), which encode from enzymes of riboflavin biosynthesis starting from GTP, were found in the yeast Saccharomyces cerevisiae and isolated.