The naturally occurring pigment curcumin, a major component of the spice turmeric, is reported to be a potent inhibitor of the initiation and promotion of many cancers. Due to its presence in the diet, one of its primary targets is the human gastric mucosa (GM) cells. Using the sensitive single cell electrophoresis method (comet assay), we found that curcumin at of 15, 25, and 50 microM caused DNA damage in GM cells and human peripheral blood lymphocytes. There was no difference between the extent of the damage in both types of cells. Damaged cells were able to recover within a period of 120 minutes. Our results indicate that curcumin may play a dual role in carcinogenesis.