To better determine the optimal combinations for empirical dual antimicrobial therapy of Pseudomonas aeruginosa infection, we evaluated the utility of a novel combination antibiogram. Although the combination antibiogram allowed modest fine-tuning of choices for dual antibiotic therapy, selections based on the 2 antibiograms did not differ substantively. Drug combinations with the broadest coverage were consistently composed of an aminoglycoside and a beta-lactam.