The objectives of this study were to investigate the potential biological activities of black cumin seed oil (BCSO) and wheat germ oil (WGO) on different cell lines. Initially, commercially available BCSO and WGO obtained by supercritical carbon dioxide extraction were analyzed in terms of tocopherol, aliphatic alcohols, and thymoquinone content via HPLC and GC analysis. Cell free antioxidant activities and total phenolic content of both oils were detected by DPPH assay and Folin-Ciocalteu method, respectively. As well as the DPPH assay, the protective effect against reactive oxygen species (ROS) was determined by microscopic observation of ROS generation in NIH-3T3 cells with or without oil samples by using an oxidation-sensitive fluorescent dye, H2DCFDA. Cytotoxicity was assessed using an MTT assay. In the case of BCSO, after exposing cells to 0.025-1.0 mg/mL and 1.0-100 mu g/mL concentrations for 24 h, the IC50 values of BCSO were 0.58, 0.51, 0.47, and 0.36 mg/mL for NIH-3T3, A549, U87, and HeLa cells, respectively. On the other hand, concentrations of WGO lower than 0.1 mg/mL did not cause a decrease in cell viability for all cell lines. Apoptotic and necrotic rates of these cell lines were investigated via flow cytometry. BCSO also exhibited proliferative efficacy for NIH-3T3 cells.