OBJECTIVE: To determine whether fluid hysteroscopic directed biopsies, in patients with endometrial cancer upstages the tumor and worsens the prognosis. STUDY DESIGN: Between January 1996 and September 2001, a total of 62 consecutive patients with endometrial cancer, treated at our institution, were randomized 3:2 to have or not to have a fluid hysteroscopic biopsy just prior to surgery. A total of 38 patients underwent a hysteroscopy after the induction of anesthesia. All patients had pelvic washings performed, followed by a hysterectomy, bilateral salpingooforectomy and pelvic +/- para-aortic lymph node dissections. Only stages I and II endometrioid type tumors or stage IIIa, secondary to positive pelvic washings, were included in the study. Eight patients in the hysteroscopy group and four patients in the control group were excluded for various reasons. Patients received post-operative radiation therapy depending on the surgical-pathological risk factors. The median follow up was 34 months. Fisher's Exact Test was performed to compare differences between the hysteroscopic (n = 30) and the control (n = 20) groups. RESULTS: We found three patients (10%) with positive washings in the hysteroscopic group compared to one (5%) among the controls (P = 0.64), with a statistical power of <20%. If the differences would persist, we would need 588 patients in each arm to obtain a power of 80%, and reach definitive conclusions. The Odds Ratio (OR) of performing a hysteroscopy and upstaging the tumor in this study was: 2.1 95% CI (0.20-21.09). Prognostic variables were compared between both groups and no differences were observed. All patients but one (dead due to intercurrent disease), were alive and with no evidence of disease at the completion of the study. CONCLUSIONS: Fluid hysteroscopy and directed biopsies may have a small risk of upstaging early endometrial cancers, but does not seem to influence prognosis.