Résumé : A series of 17 selected natural and semisynthetic 1,4-naphthoquinones were synthesized, and their growth inhibitory activity was evaluated in vitro. The compounds were tested on six human cancer cell lines using the MTT colorimetric assay. The data revealed that of the chemicals under study only lapachol, its acetate and 3-geranyllawsone displayed the highest activity, recording mean IC50 values ranging from 15 to 22 μM.