In this study, the antioxidant activity of the methanolic extracts of the black cumin (Nigella sativa L.) seeds collected from Konya, Isparta, Çorum, Burdur, Afyon and Samsun was evaluated using three different methods, specifically the β-carotene and linoleic acid system, 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity and reducing power assays. Among the six black cumin samples of different origins, the black cumin sample origins from Konya city showed the most potent radical scavenging activity in each assay, showing 94.59% (at 1 mg/mL) in the β-carotene bleaching method and 44.44% in the DPPH radical scavenging method (at 0.5 mg/mL). Positive correlations were found between the total phenolic content in the black cumin extracts and their antioxidant activities. The values of their antioxidant activity were either equivalent to or higher than those of positive BHA and BHT controls. These satisfying results lead to expect the use of black cumin seeds as health-promoting ingredients such as dietary supplements and nutraceuticals. © 2010, The Author(s). Journal compilation © 2010, Wiley Periodicals, Inc.