PURPOSE: Sexual dysfunction is an important concern of premenopausal women with early breast cancer. We investigated predictors of sexual problems in two randomized controlled trials. METHODS: A subset of patients enrolled in TEXT and SOFT completed global and symptom-specific quality-of-life indicators, CES-Depression and MOS-Sexual Problems measures at baseline, six, 12 and 24 months. Mixed models tested the association of changes in treatment-induced symptoms (baseline to 6 months), depression at 6 months, and age at randomization with changes in sexual problems over 2 years. RESULTS: Sexual problems increased by 6 months and persisted at this level. Overall, patients with more severe worsening of vaginal dryness, sleep disturbances and bone or joint pain at 6 months reported a greater increase in sexual problems at all time-points. Depression scores were significantly associated with sexual problems in the short-term. All other symptoms had a smaller impact on sexual problems. Age was not associated with sexual problems at any time-point. CONCLUSION: Among several key symptoms, vaginal dryness, sleep disturbance, and bone and joint pain significantly predicted sexual problems during the first 2 years. Early identification of these symptoms may contribute to timely and tailored interventions.