The term cancer is used for diseases in which abnormal cells proliferate without control and are able to attack with other tissues. Over various types of cancers, liver cancer is the most hurtful disease, which affects the whole body system. The aim of the present study was to investigate the efficiency against cancer cells of HepG2 cells, with quantum dots of ZnO. The cytotoxic effects were analyzed with MTT assays in range of 1-100 μg/ml. The cells were exposed to ZnO-QDs and it exhibit significant reduction, which starts from concentration 5 μg/ml (4 %; p < 0.05). The assay was justified with quantitative RT-PCR and it demonstrates, exposure of ZnO-QDs on HepG2 cells. The level of mRNA expressions was significantly up-regulated (Bax, P53, and Caspase-3), whereas the anti-apoptotic gene (Bcl-2) was down-regulated. The QDs (5 ± 2 nm) were prepared via soft chemical solution process and analyzed using FESEM, TEM and HR-TEM.