Nigella sativa (N sativa), commonly known as black seed, has been used in traditional medicine to treat many diseases. The antioxidant, anti-inflammatory, and antibacterial activities of N sativa extracts are well known. Therefore, the present study was designed to investigate the anticancer activity of seed extract (NSE) and seed oil (NSO) of N sativa against a human lung cancer cell line. Cells were exposed to 0.01 to 1 mg/ml of NSE and NSO for 24 h, then percent cell viability was assessed by 3-(4, 5-dimethylthiazol-2yl)-2, 5-biphenyl tetrazolium bromide (MTT) and neutral red uptake (NRU) assays, and cellular morphology by phase contrast inverted microscopy. The results showed NSE and NSO significantly reduce the cell viability and alter the cellular morphology of A-549 cells in a concentration dependent manner. The percent cell viability was recorded as 75%, 50%, and 26% at 0.25, 0.5, and 1 mg/ml of NSE by MTT assay and 73%, 48%, and 23% at 0.25, 0.5, and 1 mg/ml of NSE by NRU assay. Exposure to NSO concentrations of 0.1 mg/ml and above for 24 h was also found to be cytotoxic. The decrease in cell viability at 0.1, 0.25, 0.5, and 1 mg/ml of NSO was recorded to be 89%, 52%, 41%, and 13% by MTT assay and 85%, 52%, 38%, and 11% by NRU assay, respectively. A-549 cells exposed to 0.25, 0.5 and 1 mg/ml of NSE and NSO lost their typical morphology and appeared smaller in size. The data revealed that the treatment of seed extract (NSE) and seed oil (NSO) of Nigella sativa significantly reduce viability of human lung cancer cells.