A new series of manganese(III) complexes Na[Mn(L-1)(2)].3H(2)O, Na-3[MnL2(CH3COO)(4)].2H(2)O, Na[Mn(L-3)(2)].2H(2)O and amino acid Schiff bases (H2L1); [N-(2-hydroxy-1-naphthylidene)tyrosine], (H2L2); [N-(2-hydroxy-1-naphthylidene)arginine], (H2L3); [N-(2-hydroxy-1-naphthylidene)lysine] have been prepared from 2-hydroxy-1-naphthaldehyde and a-amino acids (L-tyrosine, L-arginine, and L-lysine). The structures of the compounds were identified using elemental analyses, IR, UV-VIS, H-1-NMR spectra, magnetic susceptibility measurements, and thermogravimetric analyses (TGA). All of these substances have been also examined for antibacterial activity against the pathogenic strains S. aureus, Sh. dys. typ 7, L. monocytogenes 4b, E. coli, S. typhi H, S. epidermis, Br. abortus, M. luteus, B. cereus, P. putida, and antifungal activity against C. albicans.