The set of original, highly lipophilic ultrashort acting beta-adrenoceptor antagonists containing N-phenylpiperazine fragment, labelled as 1–4, was in vitro screened for the activity against Staphylococcus aureus, Escherichia coli and Candida albicans, respectively. Following the minimum inhibitory concentration (MIC) assay by the microdilution method, all the tested molecules were practically inactive against both selected Gram-positive and Gram-negative bacterial strains showing the MICs>1.00 mg·mL-1. From structural point of view, the presence of ester group and the position of carbamoyloxy moiety within the compounds 1–4 have appeared to be the most notable factors which have decisively influenced the effectiveness against S. aureus and E. coli compared to the importance of electronic or hydrophobic interactions, which have probably been involved by the presence of N-phenylpiperazine, with different membrane components of the bacteria. The current research has also pointed out that the increase in the lipophilicity has been regarded as favourable aspect for the potency of these compounds against C. albicans. From entire evaluated set, the molecule 4 has been considered the most active against mentioned yeast with MIC=0.78 mg·mL-1.