In an ongoing project directed toward the discovery of novel treatments for diabetic complications from traditional herbal medicines, fifteen compounds, apigenin (1), apigenin-7-O-${eta}$-D-glucopyranoside (2), apigenin-7-O-(6"-O-acetyl)-${eta}$-D-glucopyranoside (3), luteolin (4), luteolin-7-O-${eta}$-D-glucopyranoside (5), luteolin-7-O-(6"-O-acetyl)-${eta}$-D-glucopyranoside (6), isorhamnetin-3-Oneohesperidoside (7), 4-O-caffeoylquinic acid (8), chlorogenic acid methyl ester (9), 4-O-${eta}$-Dglucopyranosylcaffeic acid (10), lobetyolin (11), cordifolioidyne C (12), isomultiflorenyl acetate (13), ${eta}$-sitosterol glucoside (14), and ${alpha}$-spinosterol (15), were isolated from an EtOAc-soluble fraction of the flowers of Platycodon grandiflorum (balloonflower; Campanulaceae). The structures of the compounds were identified by physical and spectroscopic methods, as well as by comparison of their data with literature values. All the isolates were evaluated in vitro for inhibitory activity on the formation of advanced glycation end products and rat lens aldose reductase.