Prostate cancer is the most common malignancy in men and the second leading cause of cancer-related mortality in men of the Western world. Lycopene has received attention due to its expected potential to prevent cancer. Alterations of the balance between proliferation and apoptosis are associated with cancer. In the present study, we evaluated the influence of lycopene on cell viability and apoptosis of human prostate cancer cells and benign prostate hyperplastic cells. We have studied prostate cells treated with lycopene for 48 and 96 hours. Using MTT assay, we observed a decrease on cell viability in all cancer cell lines after treatment with lycopene. Flow cytometer analysis revealed that lycopene promoted a maximum increase five-fold of apoptotic cells after 96 hours exposure in prostate cancer cells when compared to control group. Quantification of apoptosis can be a useful measure of cancer cell kinetics. Using real time PCR assay, lycopene treatment promoted an up-regulation of Bax gene and a downregulation of Bcl-2 gene in prostate cancer cells. No effect was observed in benign prostate hyperplasia cells. We demonstrated that lycopene inhibited cell proliferation and increased apoptosis in human prostate cancer cells. Taken together, the present study support the theory that lycopene may have a protective effect on prostate cancer, since it seems to be more efficient in terms of inhibition of the cells of early stages of abnormal growth within the prostate epithelium. The protective effect in early stages is potentially more plausible than the curative effect of lycopene in late prostate cancer.