Egyptian Leek (Allium ampeloprasum var. kurrat) has beneficial effects on human health and possess exceptional nutritional characteristics where they have strong antioxidant properties and inhibit the growth of malignancies. The current study aims to investigate the antioxidant activity and anticancer effect of phytochemical including phenolic compounds, flavonoids, tannins, and alkaloids in leek (seeds and leaves). The current results indicated that the leek leaves are good sources of ash (17.10±1.52 g/100g) and crude fibers (22.40±2.36 g/100g). While leek seeds are good source of protein (25.40±1.62 g/100g) and crude fat (11.37±2.21 g/100g). Leek leaves have high level of polyphenols (0.21±0.075 g/100g), flavonoids (0.57± 0.12 g/100g), alkaloids (0.67±0.018 g/100g) and tannins (556.90 ±0.52 mg tannic acid equivalent /100g). The phytochemicals values are higher in leek leaves than seeds. Linoleic acid (omega-6) is high in leek seeds (57.84 ±0.011 g/100g). Myricetin and Kaempferol are the most abundant flavonoids in leek seeds, while catechol and benzoic acid are the highest non-flavonoids in leek leaves. The obtained results revealed that leek leaves have higher total antioxidant capacity than leek seeds. Leek showed a high anticancer effect on breast cancer cells (MCF-7) and colon cancer cells (HCT₁₁₆) according to the IC₅₀ breast cancer cells in the form of the (MCF-7) cell line. Density function theory (DFT) showed that Pyrogallol, Catechol, and Caffeic acid have more powerful antioxidants than the other phenolic compounds.