OBJECTIVES: Selection of the most cost-effective treatment regimen of severe community-acquired pneumonia. METHODS: Direct medical expenditure on courses of treatment with levofloxacin and ceftriaxone were evaluated during this trial. “Cost minimization” analysis was chosen as a pharmacoeconomic method, and a “lost opportunities” index was calculated when using less cost-effective drugs. RESULTS: Direct medical costs in the group of patients who received levofloxacin amounted to 16,097.99 rubles, and in the group of patients who were treated with ceftriaxone they totaled 32,573.47 rubles per patient. They were made up of levofloxacin and ceftriaxone antibacterial drug treatment costs and the costs of patients' hospital stay. The cost of the drug treatment course amounted to 3,997.99 rubles for the first group (levofloxacin) and to 19,073.47 rubles for the second group (ceftriaxone); the cost of hospital stay amounted to 12,100 rubles and 13,500 rubles respectively. In the breakdown of expenditure on treatment of community-acquired pneumonia with levofloxacin, patients' hospital stay accounted for 75% of expenses, whereas drug treatment accounted for only 25% thereof; when treating with ceftriaxone, the expenditure on patients' hospital stay amounted to 40% and that on drug treatment - to 60%. The “lost opportunities” index equaled one and thus indicated that when using a more cost-effective drug (levofloxacin) for the treatment of one patient compared to a less cost-effective drug (ceftriaxone) it is possible to theoretically treat an additional patient, taking into account the difference in the costs of treatment with the drugs compared, provided the profile of antibiotic resistance is congruent with that under the conditions of the clinical study used herein. CONCLUSION: Antibacterial treatment of severe community-acquired pneumonia with levofloxacin is more cost-effective, enabling the reduction of costs by 16,475 rubles per patient compared to treatment with ceftriaxone owing to lower expenditure on drugs.