Objective-To determine cycle control, tolerability, and satisfaction among women (aged 18-45) switching from oral contraceptives (OCs) containing 30-35 mug ethinyl estradiol (EE) to Ortho Tri-Cyclen(R) LO (norgestimate 180/215/250 mug/EE 25 mug) and Loestrin(R) Fe 1/20 (norethindrone acetate I mg/EE 20 mug). Design-A subset of patients from a study comparing Ortho Tri-Cyclen LO (N = 864) with Loestrin Fe 1/20 (N = 565) was analyzed. The subset was defined as those who had taken a 30-35 mug EE-containing OC within 60 days of study start. The total number of cycles of exposure for the subset was 6,054 for Ortho Tri-Cyclen LO and 3,814 for Loestrin Fe 1/20. Additional analyses evaluated switchovers from Ortho Tri-Cyclen(R) to Ortho Tri-Cyclcn LO (N = I 11). Main Outcome Measures-Cycle control was assessed by daily diary cards reporting the frequency, severity, and duration of bleeding/spotting. Discontinuation rates due to adverse events (AEs) were considered to reflect tolerability. Satisfaction was evaluated by questionnaire. Results-The proportion of cycles in which subjects experienced breakthrough bleeding and/or spotting was significantly lower with Ortho Tri-Cyclen LO than Loestrin Fe 1/20. Discontinuations due to AEs and serious AEs were comparable for Ortho Tri-Cyclen LO (3.4% and 0.6%, respectively) and Loestrin Fe 1/20 (3.2% and 0.7%, respectively). More women on Ortho Tri-Cyclen LO versus Loestrin Fe 1/20 were very or somewhat satisfied at Cycle 6 (86% vs. 81.1%; P < 0.05) and last visit (81.6% vs. 78.1%; P < 0.05). At Cycle 6, 89.3% of Ortho Tri-Cyclen to Ortho Tri-Cyclen LO switchovers were very or somewhat satisfied, and 72.6% desired to continue taking Ortho Tri-Cyclen LO after study conclusion. Conclusions-Switchovers from OCs containing 30-35 mug EE to Ortho Tri-Cyclen LO had excellent cycle control and tolerability, and were satisfied.