Background and objective: Lower urinary tract infection is one of the most common infections among young women. The high prevalence of this infection necessitates the administration of appropriate antibiotic and minimizing the treatment period. In this study we examined and compared the effect of single-dose therapy of ciprofloxacin with seven-day therapy in women with lower UTI. Materials and Methods: The study cases comprised of 140 women aged 13-25 years with uncomplicated lower UTI who referred to Vali-Asr hospital in Arak. The patients were randomly assigned into two groups of 70. One group received a single-dose ciprofloxacin (1000 mg) while the other group received a seven-day ciprofloxacin (250 mg twice daily). Urine culture was performed for all the patients three times. In case of primary positive culture the patient would enter the study, and the second culture was carried out to investigate the response to the treatment, whereas the third culture was carried out to study the recurrence. Finally, the results of the two groups were analyzed. Results: Out of 140 patients participating in the study, 23 cases did not respond to the treatment. In the final assessment 14 non-responsive patients belonged to single-dose group while 9 patients were in seven-day therapy group. Conclusion: The research findings showed that there was no significant difference between the two groups (p=0.183) in response to the drug and recurrence. This indicates the equal efficacy of single-dose treatment and one-weak therapy of ciprofloxacin in women with lower UTI.