Thirty-one 2'-hydroxychalcones were prepared via solid-phase synthesis by base-catalyzed aldol condensation of substituted 2'-hydroxyacetophenones and benzaldehydes. Chalcones were tested for their growth inhibitory activity in three human tumor cell lines (MCF-7, NCI-H460 and A375-C5) using the SRB assay. Results revealed that several of the tested compounds caused a pronounced dose-dependent growth inhibitory effect on the tumor cell lines studied in the low micromolar range. To gain further insight on the cellular mechanism of action of this class of compounds, studies of their effect on cell cycle profile as well as on induction of cellular apoptosis were also carried out. Generally, the tested chalcones interfered with the cell cycle profile and increased the percentage of apoptotic MCF-7 cells. The results here presented may help to identify new chalcone-like structures with optimized cell growth inhibitory activity which may be further tested as potential antitumor agents.