Introduction: Acute pyelonephritis is one of the bacterial infections which is treated through injection drugs. As, using IV antibiotics has a lot of expense, thus this study was performed to compare the treatment efficacy of two regimens. IV and oral regimen and alternating oral instead of IV treatment. Materials and Methods: This clinical trial study was carried out on 54 patients \vith acute pyelonephritis without any complication in Fatemieh hospital from Aug.2002. Randomly each patient was prescribed one of the two regimes: oral ciprofloxacin (Regimen I) and IV Ceftriaxon (Regimen II). Seven patients from Regimes I, due to the incomplete treatment with the given medicine were set aside. And the rest of the cases, 24 , 48 and 72 hours after beginning the treatment were checked for disappearing or continuing the fever and clinical symptoms. Chisqure and t tests were used in the meaningful level of 5% to analyse the data.Results: Age mean and standard deviation for regimen. one were 50.40 ± 18.7 and for II 33.2± 22.4, showing no meaningful difference statistically. Both regimens were homogeneous from gender distribution. Response to treatment was 95% and 100%; respectively and showing no meaningful difference statistically. But the duration response mean (standard divination) to treatment in both regimen were 2.67 ± 0.49 days and 1.6 ± 0.63 ; respectively. And having meaningful difference statistically (P=0.000).Conclusion: This study showing that oral ciprot1oxacin is as effective as IV ceftriaxon, however, the response speed to treatment has been less.