The purpose of this study was to compare the diagnostic accuracy and specimen adequacy of in-office endometrial biopsies taken with the Novak curette and with a disposable flexible polypropylene biopsy device, the Z-sampler, in patients with endometrial cancer. Eighty women with endometrial cancer had in-office endometrial biopsies performed with the Z-sampler and the Novak curette prior to hysterectomy. The Z-sampler diagnosed 66 (82.5%) with endometrial cancer compared to 68 (85%) with the Novak curette (P = 0.724). The Z-sampler biopsies included 10 specimens (12.5%) pathologically inadequate for diagnosis, compared to 5 (6.3%) Novak curette biopsies inadequate for diagnosis (P = 0.074). When both endometrial biopsies were adequate for pathologic evaluation, the Z-sampler diagnosed 66 of 70 women (94.3%) with endometrial cancer, compared to 64 of 70 (91.4%) diagnosed with the Novak curette (P = 0.617). We did not demonstrate a significant difference in diagnostic accuracy or specimen adequacy between in-office biopsies taken with the Novak curette and those taken with the Z-sampler in patients with endometrial cancer.