Description: In 2011 the content of flavonoids (such as quercetin) in the flower of Rosa alba L. in the different phases of its development was examined. Their distribution in the different parts of the flowers was traced. Flowers from the population of white rose were examined. The study was conducted at the Institute of roses and essential oil plants Kazanlak. It was found that the white rose contains significant quantities of flavonoids, (commensurate with those of other oil types). The basic quantity is concentrated in the petals (11 mg/g). With the opening of the flower the content of flavonoids increases and reaches the maximum in fully diluted flowers (18 mg/g). The substance does not decompose under the conditions of distillation (high temperature, presence of moisture) and remains in the same amount in the rose flowers after the separation of the essential oil. It can also be used as a source for the extraction of flavonoids