purpose: to analyze the effectiveness and safety of exclusive hospital parenteral antibiotic therapy to treat puerperal endometritis in a population of low socioeconomic level. methods: a prospective clinical trial evaluated 21 puerperae with a diagnosis of postpartum endometritis, whose deliveries occurred at a university hospital by cesarean section (52.4%) or normal delivery (47.6%). the sample was characterized by low socioeconomic and educational levels. the patients were submitted to a regimen of exclusive parenteral antibiotic, only during the hospitalization period (atp-ex group). these results were compared with results obtained in a historical cohort in the same hospital (20 cases) submitted to a regimen of hospital parenteral antibiotic therapy complemented with ambulatory oral treatment (atp+vo group). the patients were evaluated clinically on the occasion of periodic return visits in order to identify cases of recurrence and infectious complications. results: one patient from the atp+vo group needed to be readmitted to the hospital on the 6th day after her discharge from the hospital with a diagnosis of endometritis recrudescence. no complications were observed among patients from atp-ex group. conclusion: for the treatment of puerperal endometritis, there was no additional advantage in using supplementary oral antibiotic therapy after patient discharge. the results using exclusive parenteral antibiotic treatment during hospitalization time indicate that it is effective and can be safely used in a population of low socioeconomic level.