Reports on the isolation and pathogenicity of some species of Gram-negative and glucose-nonfermentative bacilli have appeared in the literature since 1962. The infections caused by those organisms have become important problems as an opportunistic infection in immunosuppressed patients. Pseudomonas maltophilia is a glucose-nonfermentative aerobic Gram-negative rod widely dispersed in nature. The role of Pseudomonas maltophilia as an opportunistic pathogen is not thoroughly established, but a few papers on clinical infections associated with P. maltophilia have been published. P. maltophilia is considerably less susceptible to certain of the most commonly-used antibiotics. We have reviewed the susceptibilities of P. maltophilia to antimicrobial agents currently available and yearly changes of the strains in resistance to the antibiotics that have been extensively used.