Synthesis and antimicrobial activity of some N-substituted aza- and diaza-phenylcycloalkanes are reported. All the compounds screened in vitro show significant antibacterial and antimycotic activities. Particularly, compounds of the N-(ethoxymethyl)phenylpiperidine series, show activity towards S. aureus 1,2-1,9 superior to ampicillin. Furthermore the microbiological results indicate that the latter activity depends on the position of the phenyl-substituent.