Objective  To determine the presence of proteins related to proliferation (Ki-67) and apoptosis (Bcl-2, p53) in endometrial polyps and normal endometrium during the menstrual cycle.

Design  Retrospective study using paraffin embedded tissue.

Setting  Hospital affiliated to the university.

Population  Premenopausal patients with endometrial polyps.

Methods  Seventy-eight premenopausal patients in different phases of the menstrual cycle were submitted to polypectomy using the Bettocchi hysteroscope. Immunohistochemistry was used to detect the expression of these proteins in endometrial polyps. One hundred and eighteen normal endometrial biopsies were used as controls.

Main outcome measures  Detection of Bcl-2 and Ki-67 expression by immunohistochemistry.

Results  In endometrial polyps, Ki-67, p53 and Bcl-2 expression was detected with more frequency during the proliferative than during the luteal phase of the cycle. Similar findings were observed in the normal endometrium.

Conclusion  Endometrial polyps undergo cyclic changes in the expression of their proteins related to proliferation and apoptosis during the menstrual cycle, similar to those of the cycling endometrium.