In this study, some new Schiff bases were synthesized as antimicrobial agents using benzaldehyde derivatives and I- or 2-aminoadamantane. The structures of the synthesized compounds were confirmed by III, H-1-NMR and elementary analysis. Antimicrobial activities of the synthesized compounds were tested against some bacteria and yeast-like fungi. The antimicrobial activity of the compounds was investigated by broth microdilution method using two Gram positive (Staphylococcus aureus ATCC 25923, Enterococcus faecalis ATCC 29212) and two Gram negative (Escherichia coli ATCC 25922, Pseudomonas aeruginosa ATCC 27853) bacteria and yeast-like fungi (Candida albicans ATCC 90028, Candida krusei ATCC 6258, Candida parapsilosis ATCC 22019). The antifungal activity of 1-((2-chloro-3,4-dimethoxyhenzylidene) amino (adamantane (compound 3) against C. krusei and C. parapsilosis (minimal inhibitory concentration 32 mug/ml) was higher than that of the other tested compounds.