Introduction: For many years, hysterosalpingography was considered as the gold standard for the diagnosis of uterine cavity abnormalities, and today, hysteroscopy has been proposed as a complementary method. The present study was conducted with aim to investigate the accuracy of findings of undiagnosed filling defects in hysterosalpingography by hysteroscopy in infertile women.Methods: This cross-sectional (descriptive-analytical) study was conducted in 2020-2021 on 107 infertile women referred to Ali Ibn Abi Talib (AS) Hospital of Zahedan. Hysterosalpingography was performed for women and they had undiagnosed filling defects. After performing hysteroscopy, a questionnaire was recorded for each patient including: patient's age, age of infertility, type of infertility and hysteroscopy findings. Data were analyzed by SPSS software (version 24) and chi-square, Fisher, and Binomial tests. P<0.05 was considered statistically significant.Results: 64 patients (59.81%) had primary infertility and 43 (40.18%) had secondary infertility. The most pathological finding in hysteroscopy was polyp that was observed in 34 patients (31.77%) which were most frequent in the age range of 35-40 years. Also, 80 patients (74.76%) had abnormal hysteroscopy findings and 27 (23.25%) had normal findings. According to the Binomial test, there was a statistically significant difference between the percentage of normal findings between hysteroscopy results and filling defects without hysterosalpingography (P<0.001).Conclusion: Hysterosalpingography is a simple method for diagnosing abnormalities of the female reproductive system, but it is less sensitive than hysteroscopy. Therefore, hysteroscopy can help for more accurate and better diagnosis in examining the condition of patients with infertility