Purpose Adding taxanes to anthracycline-based adjuvant therapy improves survival outcomes of patients with node-positive breast cancer (BC). Currently, however, most patients with BC are node negative at diagnosis. The only pure node-negative study (Spanish Breast Cancer Research Group 9805) reported so far showed a docetaxel benefit but significant toxicity. Here we tested the efficacy and safety of weekly paclitaxel (wP) in node-negative patients, which is yet to be established. Patients and Methods Patients with BC having T1-T3/N0 tumors and at least one high-risk factor for recurrence (according to St. Gallen 1998 criteria) were eligible. After primary surgery, 1,925 patients were randomly assigned to receive fluorouracil, doxorubicin, and cyclophosphamide (FAC) × 6 or FAC × 4 followed by wP × 8 (FAC-wP). The primary end point was disease-free survival (DFS) after a median follow-up of 5 years. Secondary end points included toxicity and overall survival. Results After a median follow-up of 63.3 months, 93% and 90.3% of patients receiving FAC-wP or FAC regimens, respectively, remained disease free (hazard ratio [HR], 0.73; 95% CI, 0.54 to 0.99; log-rank P = .04). Thirty-one patients receiving FAC-wP versus 40 patients receiving FAC died (one and seven from cardiovascular diseases, respectively; HR, 0.79; 95% CI, 0.49 to 1.26; log-rank P = .31). The most relevant grade 3 and 4 adverse events in the FAC-wP versus the FAC arm were febrile neutropenia (2.7% v 3.6%), fatigue (7.9% v 3.4%), and sensory neuropathy (5.5% v 0%). Conclusion For patients with high-risk node-negative BC, the adjuvant FAC-wP regimen was associated with a small but significant improvement in DFS compared with FAC therapy, in addition to manageable toxicity, especially regarding long-term cardiac effects.