Temporins are antimicrobial peptides (AMPs) isolated from the skin of the red european frog Rana temporaria. They are active particularly against Gram-positive bacteria, Candida species and fungi. They have the ability to bind and permeate both artificial and biological membranes.We have recently investigated two members of this AMPs family, temporin-1Tl (Tl) and temporin-1Ta (Ta). At the same time, we developed new analogues of these peptides, among which Pro3TL (FVPWFSKFLGRILNH2) exhibiting a higher antimicrobial activity and a lower hemolytic activity than the native peptide Tl. The strong activity of Ta against gram-positive cocci and Candida, as well as its small molecular weight 13 aa residues), make this peptide TA an interesting antimicrobial compound. To elucidate the molecular basis of the interaction of the native Ta with bacterial membrane and to develop new potent analogues with improved activity, but without hemolytic activity, we performed a structure-activity study replacing L-Ala in each position of this peptide. Here we report the preliminarly results of this study.