The safety and effectiveness of Timentin were evaluated in 34 adult patients with symptomatic complicated urinary tract infections, principally due to multiply-drug-resistant bacteria. Although a wide variety of organisms, particularly gram-negative bacilli, were found, Escherichia coli was the most frequent, accounting for 14 of 45 (31 percent) pathogens isolated. Ten (22 percent) isolates were Pseudomonas aeruginosa; 11 (24 percent) were Proteus or Morganella species; three (7 percent) were Citrobacter; one (2 percent) was Klebsiella pneumoniae; two (4 percent) were Staphylococcus aureus; and two (4 percent) were enterococci. Ninety-three percent of all pathogens isolated produced a beta-lactamase. Eight (24 percent) infections were polymicrobial; seven (21 percent) were associated with bacteremia. Clinical improvement occurred in 30 of 34 (86 percent) patients. All bacteremias were cured. Although bacteriologic cure occurred in only 32 percent of patients, control of sepsis and temporary eradication of bacteria (bacteriologic improvement) occurred in 96 percent. Not surprisingly, the rates of relapses and reinfections were high. It was concluded that Timentin is a useful agent in the management of complicated urinary tract infection and offers clinicians an alternative to more toxic antibiotics, such as aminoglycosides.