Indwelling urinary catheters may act as a reservoir of bacteria and cause urinary tract infections. Removal of the bacteria adherent to a urinary catheter should reduce the incidence of catheter-associated urinary tract infections. Using several N-acylated amino acids with combinations of four different acyl residues, we investigated their efficacy in removing adherent bacteria from catheter materials in vitro. Among them, acyl phenylalanine and acyl glycine (with acyl lengths of eight or ten) exhibited the highest ability to remove adherent bacteria.