The present invention relates to a compound of formula (I) AA-AA-AA-R1—R2 (I) wherein, in any order, 2 of said AA (amino acid) moieties are cationic amino acids and 1 of said AA is an amino acid with a lipophilic R group, the R group having 14-27 non-hydrogen atoms; R1 is a N atom, which may be substituted by a branched or unbranched C1-C10 alkyl or aryl group, which group may incorporate up to 2 heteroatoms selected from N, O and S; and R2 is an aliphatic moiety having 2-20 non-hydrogen atoms, said moiety being linear, branched or cyclic. The invention further relates to formulations containing these compounds, solid supports having these compounds attached thereto, the use of these compounds in therapy, particularly as antimicrobial, anti-tumour or anti-biofilm agents and non-therapeutic uses of these compounds, particularly their use in inhibiting biofilm formation or removing a biofilm.