The efficacy of cefodizime (CDZ) in upper urinary tract infections (UUTI) and complicated lower urinary tract infections (LUTI) was assessed by analysis of the combined results of five clinical trials. Doses of CDZ 1 g i.m. daily, 1 x 2 g i.v. or i.m. and 2 x 2 g i.v. were investigated; comparative agents were cefuroxime 3 x 1.5 g and ceftizoxime 1 x 2 g. Median duration of treatment was seven days. A total of 544 patients, 61% of whom had UUTI, entered the studies. Four hundred twenty-two patients were evaluable clinically and 375 bacteriologically. The most frequent pathogen at baseline was Escherichia coli, followed by Proteus mirabilis, Klebsiella spp. and Staphylococcus aureus. Both clinical and bacteriological cure rates were above 90% in all study groups. The dosage of 1 x 2 g CDZ is recommended for the treatment of UUTI and complicated LUTI.