The comparative effectiveness and safety of carbapenems with other b-lactams and fluoroquinolones for the empirical treatment of patients with hospital-acquired pneumonia remains controversial.In the present study, a meta-analysis of 12 relevant randomised controlled trials was performed. Overall, carbapenems were associated with lower mortality than fluoroquinolones or b-lactams, alone or in combination with aminoglycosides (odds ratio 0.72, 95% confidence interval 0.55-0.95). There was no difference between the compared antibiotics regarding treatment success (1.08, 0.91-1.29), microbiological success (1.04, 0.72-1.50) or development of adverse effects (0.81, 0.46-1.43). In the subset of patients with Pseudomonas aeruginosa pneumonia, carbapenems were associated with lower treatment success (0.42, 0.22-0.82) and lower eradication of P. strains (0.50, 0.24-0.89).Carbapenems are equivalent to fluoroquinolones or b-lactams, alone or in combination with aminoglycosides, for the empirical treatment of immunocompetent adult patients with hospitalacquired pneumonia. However, there is limited evidence, based predominantly on unblinded randomised controlled trials, that carbapenems are associated with lower mortality than the comparators; this association was not observed in a subset analysis of randomised controlled trials with a high methodological quality score. In patients with Pseudomonas aeruginosa pneumonia, carbapenems are associated with worse outcomes than the comparators.