Levofloxacin is an antibacterial agent used for the treatment of a broad spectrum of acute infections in adults. This is a randomized, open-label study of the safety and effectiveness of levofloxacin compared with lomefloxacin in the treatment of adults with complicated urinary tract infections. Patients in one group are treated with 250 mg of levofloxacin, taken once daily for 7 to 10 days, and the other group is treated with 400 mg of lomefloxacin, also an antibacterial agent, taken once daily for 14 days. Patients are followed for 5 to 9 days after completion of treatment (post-therapy) to assess clinical signs and symptoms of infection. Long-term follow up (4 to 6 weeks after the end of treatment) of those patients who respond to therapy provides further evaluation of clinical signs and symptoms. The primary assessments of effectiveness include the clinical response (the resolution of signs and symptoms at post-therapy compared with those at the start of study) and the microbiological response (the eradication at post-therapy of the infectious organism identified at the start of study) An additional assessment of efficacy includes the overall clinical response, which is described as cured, improved, or failed. Safety assessments include the incidence of adverse events throughout the study, clinical laboratory tests (hematology, serum chemistry, and urinalysis) and physical examinations at the start of the study and post-therapy. The study hypothesis is that levofloxacin is at least as effective therapeutically as lomefloxacin in the treatment of adults with complicated urinary tract infections. Levofloxacin tablets, an oral dose of 250 mg taken once daily for 7 to 10 days. Lomefloxacin tablets, an oral dose of 400 mg taken once daily for 14 days.