The efficacies of many antimicrobial agents are being threatened by a global increase in the numbers of resistant bacterial pathogens--microorganisms that were once susceptible to some of these agents. In particular, antimicrobial resistance amongst strains of Haemophilus influenzae, Moraxella catarrhalis and Streptococcus pneumoniae has limited the usefulness of first-line agents in some clinical settings. Quinolones were introduced in the 1980s and represented a significant therapeutic advancement in the treatment of patients with infectious diseases. While these compounds possessed potent in-vitro activities against a wide range of gram-negative pathogens, their activities against some gram-positive and 'atypical' pathogens remained borderline. Further advancement in the development of quinolones has overcome some of these problems. The 'respiratory quinolones' represent a new generation within this class of molecules and comprise compounds possessing broad spectrum activities against gram-negative, gram-positive and atypical pathogens. This review will focus on the in-vitro activities of five new respiratory quinolones (gatifloxacin, grepafloxacin, levofloxacin, moxifloxacin and trovafloxacin), ciprofloxacin and six non-quinolone agents (azithromycin, clarithromycin, amoxycillin, co-amoxiclav, cefuroxime and co-trimoxazole) against a range of bacterial and atypical pathogens, including those that are now resistant to several of these compounds.