Complicated and recurrent urinary tract infections present intriguing clinical management problems. The underlying conditions in patients with complicated urinary tract infections are anatomical abnormalities of the genitourinary tract, neurologic disorders resulting in urinary stasis, obstruction, instrumentation, surgery, diabeters mellitus, renal transplantation, and renal calculi. In comparative studies the quinolones have been shown to be effective in 7-14-day treatment courses in complicated urinary tract infection. Several comparative trials which compare the fluoroquinolones with beta-lactam antibiotics or cotrimoxazole yielded equal or better results for the quinolones. A cost-saving option is given with some of the fluoroquinolones that can be administered parenterally and orally which enables the patient to be discharged from the hospital earlier. There are few differences in antimicrobial activity between the newer quinolones, but differences in the pharmacokinetic properties are evident. The fluoroquinolones are suitable therapeutics for complicated urinary tract infection, because they offer rapid oral absorption, high tissue concentration, broad activity against most Gram-negative and Gram-positive organisms, the possibility of a once-a-day administration, and relatively few side effects.