Inclusion Criteria:

• Woman of at least (= )18 but not older than (= )40 years of age at the time of screening;
• Good physical and mental health;
• Regular cycles with a usual length between 24 and 35 days;
• Body mass index = 18 and = 35 kg/m^2;
• Willing to give informed consent in writing.

Exclusion Criteria:

• Contraindications:

  • known or suspected pregnancy;
  • active venous thromboembolic disorder (e.g. deep vein thrombosis, pulmonary embolism);
  • presence or history of severe hepatic disease as long as liver function values have not returned to normal;
  • malignancy or pre-malignancy, if sex -steroid-influenced;
  • undiagnosed vaginal bleeding;
  • hypersensitivity to any of the components of Radiopaque Implant.
• Hypertension, i.e. systolic blood pressure >140 mmHg and/or diastolic blood pressure > 90 mmHg;
• A history during pregnancy or during previous use of sex steroids of: jaundice and/or severe pruritus related to cholestasis, gallstone formation, porphyria, systemic lupus erythematosus, haemolytic uraemic syndrome, Sydenham's chorea, herpes gestationis, otosclerosis-related hearing loss;
• Present use or use during 2 months prior to the start of Radiopaque Implant of one of the following drugs: phenytoin, phenobarbital, primidone, carbamazepine, rifampicin, oxcarbazepine, topiramate, felbamate, ritonavir, nelfinavir, griseofulvin or the herbal remedy St John's wort;
• Administration of investigational drugs within 2 months prior to the start of Radiopaque Implant