The microbiologic, pharmacokinetic, and clinical profiles of cefsulodin and ceftazidime are reviewed. Ceftazidime is a broad-spectrum beta-lactamase stable cephalosporin with excellent activity against gram-negative bacilli, including Pseudomonas aeruginosa. Cefsulodin is a narrow-spectrum cephalosporin with activity against Staphylococcus aureus and Ps. aeruginosa. Both antibiotics, which are expected to be marketed in the United States, are superior to currently available cephalosporins against Ps. aeruginosa. Cefsulodin and ceftazidime are administered by the i.m. or i.v. route, are widely distributed in body fluids and tissues, and exhibit relatively low binding to serum proteins. They are eliminated primarily through the urine, and they generally can be administered every 8 to 12 hours, depending upon the type of infection. Cefsulodin has been used successfully in the treatment of various Ps. aeruginosa infections in noncomparative studies. Ceftazidime has been successfully used as a single agent in comparative studies for Ps. aeruginosa infections. Because of its broad spectrum and its activity against penicillin-resistant and aminoglycoside-resistant Pseudomonas, ceftazidime can be used empirically as a single agent in place of combination therapy in patients with cystic fibrosis. Ceftazidime has also been useful as a single agent used empirically for treating febrile episodes in neutropenic patients and for treating hospital-acquired infections in nonneutropenic patients when Pseudomonas cannot be ruled out. Ceftazidime is a useful broad-spectrum antibiotic, particularly in the empiric therapy of nosocomial infections and in patients whose underlying conditions predispose them to Ps. aeruginosa infections. Cefsulodin may prove useful as single-agent therapy of certain infections known to be caused by Ps. aeruginosa, but its empiric use is not encouraged.