Background: Postpartum hemorrhage is a leading cause of maternal morbidity and mortality that is preventive by appropriate estimation of blood loss and its treatment. This study was undertaken to evaluate the accuracy of visual estimation of postpartum hemorrhage by clinicians and co worker who work in the obstetrics department. Methods: In this descriptive observational study, 199 educational/clinical personnel participated who worked in the obstetrics department of 3 training hospital in Mashhad in 2010. First characteristic of their occupation, educational and period of work experience recorded. Then scenes similar of postpartum hemorrhage were rebuilt by using of expired whole blood in five different volume (500, 1000, 1500, 2000, 2500, 3000 cc). Participants looked each scenes and estimated volume and necessary treatment and record in forms. Data were analyzed by SPSS software version 12 and fisher and student tests and relation between accurate volume of hemorrhage and estimated volume and treatment, occupation and experience of participants were determined. Results: Accuracy visual estimation of blood loss in different volume of postpartum hemorrhage was between 14.3% to 52%. There was no significant association between the position of the participants and accuracy of their estimation and proposed treatments. There was no association between the staffs work experience and accuracy of their estimation. Conclusion: Visual estimation of blood loss was not accurate in the majority of participants. For prevention of maternal morbidity and mortality education is necessary that to be skilled for accurate estimation of blood loss.