A LLIUM vegetables have been recorded to be used in many medical remedies for protection and fighting diseases. The aim of the study is to investigate the phenolic compounds of methanol extract of Allium porrum L. aerial parts (MEAP) and introduce the methanolic extract as a candidate for the treatment of cancer in vivo as well as explore its antitumor mechanisms in attacking tumor cells at the molecular level. Isolation of phenolic and flavonoid compounds by column chromatography has been carried out. They were purified by Sephadex LH-20, and the structures were established with the aid of spectroscopic methods (UV, EI/MS, ESI/MS, 1 H-NMR, and 13 C-NMR spectroscopy). A total of 45 female Swiss albino mice were divided into five groups. One group represents the normal control. The four remaining groups were divided as follows: two groups were injected with Ehrlich ascites carcinoma (EAC) cells intraperitoneally and the other two were injected intramuscularly (to form solid tumor), representing the positive nontreated groups. One group from each model was administrated orally the extract at a dose of 300 mg/kg body weight 3 days weekly for 21 days after 24 h from the intraperitoneal or intramuscular injection of EAC cells. The influence of the extract on the apoptotic proteins were tested in EAC cells and in solid tumor of the treated groups compared with the nontreated ones. Eleven phenolic and flavonoid compounds were isolated from the aerial parts of methanol extract of A. porrum L., and characterized as follows: quercetin-3acid, and gallic acid. The gene expressions of caspase-3, Bax, and Bcl2 proteins and DNA fragmentation test were performed in the EAC cells. Hematological profile was conducted on mice's blood in addition to the Immuno-histochemical determination of P53 protein in solid tumors. MEAP has abundant phenolic compounds. It exhibits tumor suppressing mechanisms through the coordination between the apoptic proteins and DNA fragmentation in the EAC or solid cancer cells. MEAP is suggested to be a potent anticancer agent.