Free radicals can cause various degenerative diseases such as cancer and cardiovascular disease. Flavonoids have antioxidant abilities that inhibit damage from free radicals. The roselle antioxidant mechanism is associated with high flavonoid content. Red and purple roselles are two varieties of roselle (Hibiscus sabdariffa L.) cultivated in Indonesia. The aim of this research was to analyze the differences in flavonoid content and antioxidant activity in the calyces of two varieties of roselle (Hibiscus sabdariffa L.), red and purple. Total flavonoid analysis and antioxidant activity testing were done by spectrophotometry in the visible region. Total flavonoid content was analyzed by pretreatment with aluminium chloride and sodium acetate. Antioxidant activity was tested with 2,2-diphenyl-1-picrylhydrazyl. The total flavonoids for both red and purple roselle calyces ethanolic extract were 27.55 and 39.18 mg quercetin equivalent per gram. The half maximal inhibitory concentration values obtained for both red and purple roselle calyces ethanolic extract a were 51.59 and 42.17 μg/mL. The total flavonoid content and antioxidant activity of purple roselle calyces ethanolic extract was higher and stronger than red roselle calyces ethanolic extract.