PIP: In order to determine the causes of irregular bleeding, a stereoscopic examination was conducted on 58 IUD users aged 25-45 years between March 1986 and February 1987. Included in the study were 34 cases who experienced excessive and prolonged menstrual bleeding after IUD insertion and 24 controls. Among the cases, 18 women had IUDs in place for 1-7 years, and women had them 3 for 8-11 years, while all of the controls has IUDs in place for 1-7 years. Stereoscopic examinations were conducted during the bleeding period, the IUDs were removed during the examinations, and biopsies of the endometria were taken at the locations where the IUDs used to be. Stereoscopic examination of the cases showed the displacement, deformity, and breaking of the IUDs in 6 cases. Most of the metal IUDs had lost gloss. Besides, uterine cysts and polyps were also causes of bleeding. More swelling, congestion, growth of endometria, and intra-uterine blood clots were observed among the cases than controls. Pathological examinations of endometria confirmed the results of stereoscopic observation. It was concluded that displacement, deformation, breaking of IUDs, and inflammation of endometria were the principal causes of excessive uterine bleeding. Stereoscopic examination has important clinical applications for determining the causes of uterine bleeding associated with IUD use and for subsequent treatment.