Various Diels Alder cycloaddition conditions have been used to optimise the preparation of cytotoxic 6-alkyl-1,4-naphthoquinones, which were subsequently transformed into 6(7)-alkyl-2-hydroxy-1,4-naphthoquinones. The compounds thus prepared were evaluated for their cytotoxic activity against several neoplastic cultured cell lines and some of them showed IC50 values below the muM level.