Background: Indirect genetic diagnosis using polymorphic DNA markers can detect carriers of hemophilia A. This technique is preferable in developing countries because of its simplicity and cost effectiveness compared to direct mutation analysis. In the present study, we examined usefulness of intragenic marker BclI restriction fragment length polymorphism (RFLP) at intron 18, for carrier detection. How this marker is informative was tested in 102 members of 16 hemophiliac families from Sistan and Baluchestan province, Southeast of Iran. Methods: Blood samples were obtained from 29 hemophilia A patients and 73 of their relatives, after taking informed consents. DNA was extracted using proteinase K digestion followed by DNA precipitation. Factor VIII gene polymorphism was identified by the polymerase chain reaction/RFLP which is both sensitive and economical. Results: Our results showed that almost 69.8% of X-chromosomes had restriction site for BclI enzyme. The heterozygosity rate for BclI polymorphism in tested women was 61.4%, signifying the usefulness of this marker in carrier detection. The informative rate respecting this polymorphism was 43.7% meaning that a remarkable percent of families from the target population could be diagnosed using this marker alone. Conclusion: In Sistan and Baluchestan province where there is limited access to sophisticated facilities of molecular diagnosis, use of PCR-based analysis of DNA polymorphism in the BclI locus can be used to identify a remarkable percentage of the carriers and even for prenatal diagnosis. Meanwhile, it is necessary to evaluate the effectiveness of other polymorphic DNA markers to enhance the informative rate.