Our objective was to investigate the presence of focal p53 expression in relation to proliferation rates in adenomyotic lesions during the menstrual cycle and in women on oral contraception. Fifty-nine perimenopausal patients with menorrhagia and adenomyosis were submitted to endometrial resection. The procedure was carried out during menstruation (n = 14), during the proliferative phase (n = 15), during the luteal phase (n = 20) or following the use of oral contraceptives (n = 10). The number of Ki-67-positive cells was low during menstruation, during the luteal phase and following the use of progestins. In the proliferative phase, on the other hand, there was a significant increase in the percentage of Ki-67-positive cells. Focal p53 expression was detected mainly during the proliferative phase of the menstrual cycle when proliferation rates were high. PTEN expression was detected in all cases irrespective of the phase of the menstrual cycle or use of oral contraception. We conclude that proliferation rates in adenomyotic lesions undergo marked cyclic variations and this affects the percentage of cases showing focal p53 expression in the glandular epithelium.