Gram-negative non-fermenting bacilli, particularly Pseudomonas aeruginosa and Acinetobacter spp., are important opportunistic pathogens in hospitalized patients, contributing to their morbidity and mortality. Recently, a rapid increase in frequency of multidrug-resistant clinical strains is being recorded, making the available therapeutic options very limited. Apart from the development of novel classes of antimicrobials, there is renewed interest in the use of old agents or new combinations of available drugs. Numerous in vitro investigations have been reported on the efficacy of different antimicrobials; however, they should be evaluated in experimental infection models and clinical trials. Novel approaches are being investigated, such as inhibition of virulence factor expression by pathogens or inhibition of their metabolic pathways. The use of bacteriophages, particularly those genetically modified, remains an alternative option in the therapy of infections caused by multidrug-resistant strains. Several vaccines against P. aeruginosa are under development. Apart from therapy with antimicrobial agents, eradication of outbreaks comprises implementation of strict infection control measures and prudent use of antimicrobials.