The presence of lupus anticoagulant (LA) and anticardiolipin antibodies (ACA) are associated with recurring pregnancy loss. Of 387 consecutive patients investigated at a Recurring Miscarriage Clinic over a three year period, 63 (16%) were positive for LA and ACA or both. Fifty-nine patients by definition were classified as having antiphospholipid syndrome and four also had systemic lupus erythematosus (SLE). Fifty-three subsequent pregnancies occurred in 63 patients and of these 37 ended in a live birth giving an overall livebirth rate of 70%. Treatment included low dose aspirin alone in 37 pregnancies and low dose aspirin and low molecular weight heparin (LMWH) in 16 pregnancies. The decision for treatment was made empirically on past obstetric history and level of LA and ACA, and past history of venous thromboembolic disease. Obstetric outcome was worst in the group who were positive for both LA and ACA, with a success rate of 53%, compared to 72 or 81% in the single parameter groups. Complications in the 37 successful pregnancies included eight Caesarean sections, four cases of intra-uterine growth restriction, one case of pregnancy induced proteinuric hypertension, one deep vein thrombosis and one pulmonary embolism. Patients with antiphospholipid syndrome are at high risk of pregnancy loss as well as maternal morbidity, especially thrombo-embolic disease. A randomised prospective controlled trial is necessary to determine the optimum therapy for pregnancy conservation and thrombprophylaxis.