The present invention relates to new compounds being structurally and functionally similar to Actinomycin D and to combinatorial libraries of such compounds. The Actinomycin D analogues according to the present invention comprise two linear or cyclic peptide moieties constituted by $g(a)-amino acids, $g(b)-amino acids and/or longer chain $g(v)-amino acids, and a difunctional group which preferably is a cyclic entity, in particular, an aromatic or heteroaromatic entity acting as an intercalator group. Specific compounds and a library of such compounds may be prepared using conventional solid phase peptide synthesis (SPPS) methodologies. The novel compounds are expected to have affinity for DNA and RNA, and libraries thereof may therefore advantageously be used for screening purposes. Furthermore, a novel double-combinatorial technique that may be used in the preparation of librairies of broader classes of compounds has been developed.