The activity of matrix metalloproteinases (MMPs) in the uterine flushing and endometrial tissue of normal adult women wearing FCu-IUD (fixed Cu-IUD) or FICu-IUD (indomethacin-releasing FCu-IUD) was observed by using zymography on SDS-PAGE containing gelatin. The results showed that the activity and kinds of MMPs in FCu-IUD group were increased significantly as compared with themselves before being inserted FCu-IUD. However, compared with the FCu-IUD group, the activity of some kinds of MMPs in the FICu-IUD group was decreased significantly.These data suggest that IUD can enhance the activity of MMPs in human endometrium, intermediated by prostaglandins, and MMPs may have relation to IUD-induced menorrhagia and indomethacin reduces IUD-induced menorrhagia by partly inhibiting MMPs synthesis.