In breast cancer cyclooxygenase-2 expression is related with high local estrogen receptor levels and consequent poor outcomes, but the clinical relevance of cyclooxygenase-2 is still unclear. We analyzed, by immunostaining, cyclooxygenase-2 and progesterone receptor expression in 31 cases of women with invasive ductal carcinoma, from Child and Women department of Cova da Beira Medical Center. Cyclooxygenase-2 and progesterone receptor expression was observed in 64.5% and 54.8% of the tumors, respectively. We verified that tumors with progesterone receptor expression had lower size and the majority of women with these tumors had no axillary node metastasis, when compared to tumors with positive progesterone receptor. Similar results were found when a correlation between progesterone receptor, cyclooxygenase-2 and clinicopathological factors was performed. These results suggest that progesterone receptor has a protective role in breast cancer by inflammatory pathway modulation. COX-2+/PR+ seems to be a marker of better behavior in ductal invasive breast cancer. We speculate if cyclooxygenase-2 determination may have be a clinical usefulness in clinical practice. It’s expected that further studies may clarify this issue.