BACKGROUND: Recurrent miscarriage has been associated with antiphospholipid syndrome (APS) and other prothombotic conditions. We tested the hypothesis that women diagnosed as having APS as an aetiological factor for their miscarriages were at higher risk of thrombosis than those with idiopathic recurrent miscarriage. METHODS: A retrospective case–control study was performed using validated questionnaires. A total of 141 women with recurrent miscarriage and APS alone were matched with 141 women with idiopathic recurrent miscarriage for age, number and type of pregnancy loss and number of years of follow-up. A subgroup of eight women included those who initially presented with recurrent miscarriage, thrombosis and APS. RESULTS: The mean length of follow-up was 7.3 years and response rate 74%. The incidence of thrombosis was similar in the recurrent miscarriage and APS women (6/1000 women-years) and in the idiopathic recurrent miscarriage women (2/1000 women-years) (P=0.18). All eight women who presented with recurrent miscarriage, APS and thrombosis reported further thrombotic events. CONCLUSIONS: Both idiopathic and APS-associated recurrent miscarriage were associated with a similar long-term risk of thrombosis.