Alantolactone and isoalantolactone, main bioactive compounds that are present in many medicinal plants such as Inula helenium, L. Inula japonica, Aucklandia lappa, Inula racemosa, and Radix inulae, have been found to have various pharmacological actions including anti-inflammatory, antimicrobial, and anticancer properties, with no significant toxicity. Alantolactone and isoalantolactone have been reported for their wide spectrum of biological effects, including antifungal, anthelmintic activities, antimicrobial activities, anti-inflammatory activities, antitrypanosomal activities, and antiproliferative effects on several cancer cell lines, such as colon, melanoma, ovary, prostate, lung, and leukemia. Alantolactone isolated from Inula helenium (Compositae), a traditional Chinese medicinal herb, provides an effective inhibitory activity for cell growth against MK-1, HeLa, B16F10, and K562 cell lines. Many other human cancer cell lines, including U87 glioma cells, Bel-742, SMMC-7721 and HepG2 liver cancer cells, PANC-1 pancreatic carcinoma cells, A59 lung cancer cells, colon adenocarcinoma HCT-8 cells, CNS cancer cell line SF-295, leukemia HL-60, Hepa1c1c7 cells, BPRc1 Hepatic cancer cells, and HCT-8 colon cancer cells, have also been reported for apoptosis caused by alantolactone.