Ceforanide (BL-S 786) is a new long-acting parenteral cephalosporin which has the major pharmacologic advantage of requiring only twice a day dosage. We treated 28 adult patients with community-acquired bacterial pneumonia using doses of 500 or 1000 mg every 12 hours. Twenty-four of 28 infections were due to Streptococcus pneumoniae and/or Hemophilus influenzae, and all pathogens were susceptible in vitro to both cephalothin and ceforanide. Patients were treated for a mean of 7.5 days, and all showed a good clinical and radiographic response with no mortality. Of the 13 patients with H. influenzae, the organism could still be recovered during therapy in 9/12 and post therapy in 3/8. One clinical superinfection (sepsis due to Pseudomonas aeruginosa) occurred during therapy. Side effects with therapy included thrombocytosis (15), asymptomatic eosinophilia (5), and mild elevation of the serum transaminases (3). These studies suggest that ceforanide is a safe and effective agent for the treatment of adult patients with bacterial pneumonia due to S. pneumoniae; further experience in therapy of H. influenzae is needed because of frequent failure of ceforanide to eradicate this organism from the sputum.