Ethanolic extract of Gelsemium sempervirens (family: Loganiaceae), henceforth to be called EEGS, is used in various traditional systems of medicine. In homeopathy, EEGS is known as mother tincture of G. sempervirens, which is generally used to treat pain and respiratory ailments. We demonstrated earlier anticancer activity of crude EEGS by in vitro studies on human HeLa cells. To test the hypothesis if nanoparticle-encapsulated extract (now onwards to be called NEEGS) could enhance cellular uptake and thereby improve bioactivity, we formulated nanoparticle encapsulation based on poly (lactide-co-glycolide) (PLGA) and confirmed encapsulation by scanning electron microscopy (SEM) and atomic force microscopy. EEGS was encapsulated with 81.6% efficiency in PLGA biodegradable nanoparticle formulation and F68 (polyoxyethylene-polyoxypropylene) was used as a stabilizer. Dynamic laser light scattering and SEM indicated a particle diameter of 122.6 nm. The zeta potential of the drug-loaded nanoparticles was –14.8 mV. NEEGS was characterized for their biological activities in a skin cancer cell line A375 in vitro. NEEGS exhibited relatively rapid (30 min) and more efficient cellular uptake than their un-encapsulated counterpart (45 min). Analysis of data of apoptosis study using Annexin V-FITC, terminal transferase dUTP nick end labeling assay and DNA ladder revealed that encapsulated EEGS was more potent than their un-encapsulated counterpart in inducing apoptosis of A375 cells. Reverse transcriptase-polymerase chain reaction data of survivin, cyclin-D1, caspase-3, PCNA and p53 also corroborated well to suggest greater potentials of NEEGS as anticancer agents.