The development and progression of esophageal cancer is associated with multiple alterations in the genome, including loss of the tumor suppressor phosphatase and tensin homolog deleted from the chromosome 10 (PTEN) gene. The purpose of this study was to determine the effects of adenovirus-mediated MMAC/PTEN expression on the growth and survival of human esophageal cancer cells in vitro and in vivo. We found that compared to control cells, overexpression of PTEN significantly suppressed growth and induced apoptosis in esophageal cancer cell lines Eca-109 and TE-1 via downregulation of Bcl-2 expression and changes in cell-cycle progression. Adenovirus PTEN also inhibited the growth of subcutaneous tumor xenografts by significantly reducing tumor size in vivo. Thus our results confirm the proposed functional role of MMAC/PTEN as a regulator of esophageal cancer progression in vivo and in vitro. PTEN might be an important biological marker and potential therapeutic target in the treatment of human esophageal cancer.