Carbon dioxide-enriched atmospheres are used to reduce decay incidence and severity and extend the postharvest life of strawberries. However, depending on the cultivar, carbon dioxide concentrations of ≥20% can be detrimental to color (change from red to purple) and flavor (development of off-flavors). Our objective was to determine the effect of elevated carbon dioxide levels on the stability of the anthocyanins and other phenolic compounds to examine their role in color changes of strawberries. Freshly harvested strawberries were placed in jars ventilated continuously with air or air enriched with 10%, 20% or 40% carbon dioxide at 5°C for 10 days. Anthocyanins and other phenolics were extracted at 0, 5, and 10 days from homogenized samples. The samples were purified using Sep-pac C18 cartridges. The purified methanolic extract was injected directly into HPLC coupled to a photodiode array detector. Cyanidin-3-glucoside, pelargonidin-3-glucoside, and pelargonidin-3-rutinoside were identified as the major anthocyanins. After 5 and 10 days in storage there was a reduction in the total amount of anthocyanins. This degradation was lower in air than in carbon dioxide-treated strawberries, but the anthocyanin profile remained the same. Flavonols (e.g., quercetin and kaempferol derivatives) and phenolic acids (e.g., ellagic acid) decreased during storage, and this decrease was exacerbated by elevated carbon dioxide atmospheres. Carbon dioxide-induced changes in the quantities of the previously listed anthocyanins and phenolic compounds may be the cause of color changes from red to purple in strawberries.