Thyme, rosemary, black pepper, and cumin were packaged in 100% N-2 (MAP) or air (AP) and gamma-irradiated at 0, 6, or 14 kGy. The changes in antioxidant and antimicrobial activities of their essential oils and methanol extracts were determined. Irradiation decreased the total phenolic content of AP samples (except thyme). Irradiation increased the 2,2-diphenyl-2-picrylhydrazyl radical scavenging activity in thyme extract and cumin essential oil in AP, but it decreased the activity in cumin extract (MAP). Ferric reducing antioxidant power was increased in rosemary (MAP) and thyme (MAP and AP) essential oils and rosemary (MAP and AP) and black pepper (AP) extracts, whereas it was decreased in the thyme extract (MAP) by irradiation. Irradiation increased the beta-carotene-linoleic acid bleaching based antioxidant activity in essential oils of thyme (AP) and black pepper (MAP), but it decreased the activity in cumin extract (MAP). Irradiation increased antimicrobial activities of thyme and cumin essential oils.