The Oral Contraceptives part of the Safety of Estrogens in Lupus Erythematosus National Assessment (OC-SELENA) study was a prospective, randomized, double-blind trial carried out at 15 U.S. centers that examined the effects of oral contraceptives on disease activity in 183 premenopausal women with systemic lupus erythematosus. Initially, disease was inactive in 76% of participants and active but stable in the remaining 24%. Participants were assigned to receive 35 μg triphasic ethinyl estradiol plus 0.5, 0.75, or 1 mg norethindrone, or placebo, for 12 28-day cycles. None of the subjects had moderate to high titers of anticardiolipin antibodies, lupus anticoagulant, or a history of thrombosis. Just over one third of patients in each group failed to comply throughout the 12-month study. Only seven of 91 women given oral contraceptives and seven of 92 placebo recipients had a severe flare of disease during the study. Two flares in the active treatment group occurred when the study drug was omitted. On Cox proportional-hazards analysis, the relative risk (RR) of a severe flare occurring during OC treatment, compared with placebo, was 0.93 (95% confidence interval [CI], 0.33–2.65). The estimated difference was less than the maximum clinically acceptable difference. Participants in both groups who had active disease at the outset were likelier than those whose disease was inactive to have a severe flare. The estimated RR, adjusted for treatment, was 3.5 (95% CI, 1.23–9.99). Rates of moderate or mild flares were similar in the treatment and placebo groups. The likelihood of having at least one flare of any degree during 12 months of follow up was 76% for actively treated patients and 69% for those in the placebo group (RR, 1.09; 95% CI, 0.76–1.55). One OC-treated patient had deep venous thrombosis (DVT) and one had a clotted graft. In the placebo group, there was one case each of DVT, ocular thrombosis, and superficial thrombophlebitis, and one woman died after the trial ended. These findings endorse the use of oral contraceptives, including estrogen, as a birth control measure by women having inactive or active but stable systemic lupus erythematosus. These patients are at relatively low risk of developing thrombosis.