This study aims to evaluate the presence of flavonoids in flowers of different Allamanda species and quantify the rutin by high performance liquid chromatography. The gradient method employs a Phenomenex C18 column with methanol, acetonitrile and water acidified with constant flow of 0.8 mL min-1 and photo diode array (PDA) detection at 355 nm. It was possible to detect several flavonoids in the flowers extract, including rutin with Rt 29.6 ± 0.5 min. Good linearity (correlation coefficient >0.999) for calibration curve of standard rutin was achieved. The limits of detection and quantitation were 0.25 and 2 μg mL-1, respectively. The accuracy, in terms of recovery percentage, ranged from 98.18% to 100.9%. The following concentrations of rutin in the ethyl acetate fraction were obtained: A. cathartica 18.46 ± 0.04, A. schottii 24.85 ± 0.08 and A. blanchettii 45.22 ± 0.08 mg 100g of fresh flowers. The Allamanda is an excellent font of flavonoids.