The glycoalkaloids present in Eastern black nightshade were isolated, purified, and identified. An analytical system using high-performance liquid chromatography has been developed for their quantitation. The total glycoalkaloid content of nightshade berries was 12-14 mg/g and the alkaloids found were β-solamargine (2.4 mg/g), α-solamargine (3.3 mg/g), α-solasonine (4.9 mg/g), α-chaconine (0.5 mg/g), and α-solanine (1.0 mg/g).