Given the critical role ofCYP19in estrogen synthesis, we investigated the influence ofCYP19gene polymorphisms on the clinical outcome of lymph node- (LN-) negative, hormone receptor- (HR-) positive early breast cancers. Genotyping for theCYP19polymorphisms rs4646 (A/C), rs1065779 (A/C),CYP19(TTTA)n (short allele/long (S/L) allele using the 7 TTTA repeat polymorphism as the cut-off), and rs1870050 (A/C) was performed on 296 patients with LN-negative, HR-positive breast cancers. All patients received adjuvant hormonal therapy. Associations were examined between these 4 genotypes and 6 common haplotypes ofCYP19and distant disease-free survival (DDFS), disease-free survival (DFS), and overall survival (OS). Patients were divided into the 6 subhaplotypes ofCCLA(41.1%),AASA(17.1%),CASA(11.9%),CCLC(8.9%),CCSA(7.5%),AASC(8.9%), and others (4.6%). In premenopausal patients, haplotypeAASAwas significantly associated with a poor DDFS (adjusted hazard ratio (aHR), 3.3;P=0.001), DFS (aHR, 2.5;P=0.0008), and OS (aHR, 2.9;P=0.0004) after adjusting for age, tumor size, tumor grade, estrogen receptor status, progesterone receptor status, chemotherapy, pathology, adjuvant hormone therapy, menopausal status, and radiotherapy. Furthermore, haplotypeAASAremained a negative prognostic factor for premenopausal patients receiving adjuvant chemotherapy in terms of DDFS (aHR, 4.5;P=0.0005), DFS (HR, 3.2;P=0.003), and OS (HR, 6.4;P=0.0009). However, in postmenopausal patients, haplotypeAASAwas not associated with a poor prognosis, whereas theAASChaplotype was significantly associated with a poor DFS (aHR, 3.1;P=0.03) and OS (aHR, 4.4;P=0.01). Our results indicate that, in patients with LN-negative, HR-positive breast cancers, genetic polymorphism haplotypeAASAis associated with poor survival of premenopausal women but does not affect survival of postmenopausal women.