Parallel to the elongation and the thickening of the carrot (Daucus carota L.) root, there is an active synthesis of sugars, mainly sucrose, and carotenes, mainly β-carotene. The contents of both groups of substances reach their maximum at the end of the 3rd mo after seeding, then remain almost constant. Organic and amino acids, which are present in rather low concentration, increase slowly with age. In a growing carrot, pyruvic acid is the most plentiful acid, followed by isocitric and malic. Phenolic compounds, abundant in the very young root, decrease rapidly during the first 3 mo, then remain at a plateau level up to harvest date.