Previously we found that a fruit-derived polyphenol fraction caused an inhibition of proliferation and an induction of differentiation markers in Caco-2 human colon cancer cells. In the present work, we sought to determine if individual polyphenols would exert similar actions. Proliferation was inhibited by several polyphenolic molecules including gallic acid, ellagic acid, quercetin and resveratrol. In Caco-2 cells, growth inhibition was accompanied by increased specific activities of two differentiation markers, alkaline phosphatase and dipeptidyl peptidase, but not of aminopeptidase. Increased enzyme activities were not seen in HT29 and SW1116 colon cancer cells. In Caco-2 cells there were additive effects of butyrate or valproate and polyphenolic molecules. Histone acetylation was not greatly affected by the polyphenols. Cycloheximide inhibited protein synthesis in the 3 cell types examined but paradoxically, in Caco-2 cells it caused increased specific activities of alkaline phosphatase and dipeptidyl peptidase. Several plant polyphenols can inhibit the growth of colon cancer cells but increased specific activity of some differentiation markers seen in Caco-2 cells did not appear to be a general phenomenon in colon cancer cells.