Aims: To evaluate the sampling adequacy and diagnostic accuracy of the endometrial SAP-1 sampling device in detecting endometrial lesions based on histopathological examination. Materials and Methods: In total, 182 patients who required an endometrial biopsy were enrolled in this study. All of the patients underwent endometrial biopsies with the SAP-1 sampler prior to hysteroscopy (169/182) or dilatation and curettage (D&C) (13/182). Endometrial tissues were obtained at biopsy for histopathological examination. Results: Adequate endometrial specimens were obtained in 148 of 182 patients (81.32%). Menopause (p = 0.000), endometrial thickness (p = 0.004), and the types of endometrial diseases (p = 0.009) differed significantly between the two groups. Among the 169 patients who underwent hysteroscopy, sampling scratches were observed in the uterine cavity in 147 cases (86.98%). Compared to traditional methods, such as hysteroscopy and D&C, the sampling diagnostic sensitivity, specificity, and positive and negative predictive values were 82.35%, 100%, 100%, and 97.76% for endometrial carcinoma (n=17) and 37.5%, 100%, 100% and 97.76% for endometrial atypical hyperplasia (n=8), respectively. Those that were misdiagnosed occurred because the lesions were focal or localized in a small part of the uterine cavity. The sampling diagnostic sensitivity for polyps (n=32) was 12.5%. Two patients with submucosal leiomyoma went undiagnosed based on the sample specimens. Conclusion: Endometrial sampling using the SAP-1 sampler is a minimally invasive alternative technique for obtaining adequate endometrial specimens for histopathological examination. The SAP-1 sampler was useful in detecting endometrial carcinoma and atypical hyperplasia cases that were not highly suspected to be localized; however, this method was not useful in detecting endometrial polyps and submucosal leiomyomas.