BACKGROUND: The estimated annual global burden of miscarriage is 33 million out of 210 million pregnancies. Many women undergoing miscarriage have surgery to remove pregnancy tissues, resulting in miscarriage surgery being one of the most common operations performed in hospitals in low-income countries. Infection is a serious consequence and can result in serious illness and death. In low-income settings, the infection rate following miscarriage surgery has been reported to be high. Good quality evidence on the use of prophylactic antibiotics for surgical miscarriage management is not available. Given that miscarriage surgery is common, and infective complications are frequent and serious, prophylactic antibiotics may offer a simple and affordable intervention to improve outcomes. METHODS: Eligible patients will be approached once the diagnosis of miscarriage has been made according to local practice. Once informed consent has been given, participants will be randomly allocated using a secure internet facility (1:1 ratio) to a single dose of oral doxycycline (400 mg) and metronidazole (400 mg) or placebo. Allocation will be concealed to both the patient and the healthcare providers. A total of 3400 women will be randomised, 1700 in each arm. The medication will be given approximately 2 hours before surgery, which will be provided according to local practice. The primary outcome is pelvic infection 2 weeks after surgery. Women will be invited to the hospital for a clinical assessment at 2 weeks. Secondary outcomes include overall antibiotic use, individual components of the primary outcome, death, hospital admission, unplanned consultations, blood transfusion, vomiting, diarrhoea, adverse events, anaphylaxis and allergy, duration of clinical symptoms, and days before return to usual activities. An economic evaluation will be performed to determine if prophylactic antibiotics are cost-effective. DISCUSSION: This trial will assess whether a single dose of doxycycline (400 mg) and metronidazole (400 mg) taken orally 2 hours before miscarriage surgery can reduce the incidence of pelvic infection in women up to 2 weeks after miscarriage surgery. TRIAL REGISTRATION: Registered with the ISRCTN (international standard randomised controlled trial number) registry: ISRCTN 97143849 . (Registered on April 17, 2013).