The metal complexes with organic ligand derived from isothiosemicarbazide fragment has received considerable attention due to their bioinorganic applications. In recent years, research has proved the ability of isothiosemicarbazones and their complexes to be antimicrobial, antiviral, anti-inflammatory and chemotherapeutic agents, potentially useful for inhibiting the activities of cancer cells [1-3]. The aim of this work was the synthesis of some metal complexes with 2hydroxybenzaldehyde N(4)-allyl-S-methylisothiosemicarbazone (HL) and their characterization, and investigation of antimicrobial and antiproliferative activity through in-vitro experiments. The ligand was obtained by refluxing in ethanol an equimolar amount of N(4)-allyl-3-thiosemicarbazide with 2-hydroxybenzaldehyde in the presence of iodomethane. Metal complexes were synthesized using ligand HL and different metal salts. All complexes were characterized by 1H, 13C NMR, IR, UV-Vis, elemental and thermal analysis, molar conductibility, and magnetic susceptibility. In addition, the structures of the ligand and of six complexes has been determined by Xray diffraction method. The complexes were tested for their in-vitro antimicrobial activity against: Staphylococcus aureus, Enterococcus faecalis, Escherichia coli, Salmonella abony and Candida albicans strains. Also, the antiproliferative activity was tested on human leukemia HL-60, cervical cancer HeLa and normal MDCK cells. The physical-chemical analyses confirmed the newly obtained structures. The isothiosemicarbazone acts as a mononegative tridentate ligand coordinating to the metal center through the O–N–N chelating system. From the tested complexes, the Cu(II) and Fe (III) complexes have shown significant biological properties. References 1. A. Logua, M. Saddi, V. Onnis, C. Sanna, C. Congiu, R. Borgna, M. Cocco, Int. J. Antimicrob. Ag. 2005, 26, 28. 2. M. Cocco, C. Congiu,V. Onnis, M. Pellerano, Al. Logu, Bioorg. Med. Chem. 2002, 10, 501 3. A. Plumitallo, M. Cardia, S. Distinto, A. Logu, E. Maccioni, IL Farmaco 2004, 59, 945. * Corresponding author, tel. +40722476215, e-mail address elenaandmihaela@yahoo.com (Elena Pahontu).