A disposable, plastic, sterile instrument, RetrievetteR, for the retrieval of 'missing' threads of intrauterine contraceptive devices (IUD) at routine gynecological investigations was developed and tested in 80 patients. In 64 instances, the threads were found and easily drawn out through the cervical canal. In the remaining 16 cases, where the threads were not found, this was due to already expelled IUD in 6, too short threads in 5, inverted IUD in one, IUD which had partly perforated the uterine wall in one, unknown factors in 2 cases where the women chose to keep a correctly placed IUD in spite of missing threads and, finally, in only one case due to method failure. In the latter case, a correctly placed IUD with threads of normal length was later extracted under general anaesthesia. It is concluded that this instrument can help the physician avoid more complicated and unpleasant procedures with ultrasonic or X-ray localization and subsequent IUD extraction under local or general anesthesia in women with missing IUD threads.