Following a review of the latest methods of treating infections of the urinary ways, the pharmacokinetic and clinical results of a new antibiotic, Carfecillin, are reported. The examination was carried out on a total of 10 volunteers. The substance showed good serum levels and fair renal excretion with both the 250 mg and the 500 mg p.o. doses. The clinical study was carried out on a double blind basis versus a standard reference (indanyl ester of carbenicillin) in 26 patients and showed the electivity of the antibiotic in the oral treatment of urinary infections under well tolerated conditions.