Aphidicidal activity of an aqueous fraction of stems of Serjania schiedeana Schltdl. (Sapindaceae) was evaluated in laboratory bioassays by artificial diet against adult female apterous sugarcane aphid, Melanaphis sacchari (Zehntner) (Hemiptera: Aphididae). The aqueous fraction of stems of S. schiedeana at concentrations of 1,000, 2,500, 5,000, and 10,000 ppm killed 34, 36, 56, and 82% of the aphids, respectively, during the 72-hour experimental period. The positive check imidacloprid (Confial^®) at 1% killed 100% of the aphids and the negative check (artificial diet) killed only 4%. The mean lethal concentration (LC₅₀) of the aqueous fraction treatments was 3,013 ppm. A phytochemical profile of the aqueous fraction of stems of S. schiedeana was positive for alkaloids, flavonoids, and tannins. Tannins were also major compounds by HPLC analysis, revealing the presence of proanthocyanidins. Results suggested S. schiedeana might have important potential for development of new bioinsecticides, providing a better option than synthetic insecticides.