A study was conducted to investigate the clinical and pathological characteristics of breast cancer in patients with a family history (FH). Among 4,481 primary breast cancer patients, 394 (8.8%) had families which included two or more breast cancer patients within three generations (FH(+)group). This group was compared with the remaining 3,969 patients (FH(-) group) with the following results: (1) The tumor diameter in the FH(+) group was slightly less than that in the FH(-) group [not significant (NS)], with fewer lymph node metastases (P < 0.05); (2) the positive rates for the estrogen receptor were 52% (138/266) and 49% (1,216/2,481), respectively (NS); (3) expression of the c-erbB-2 protein was observed in 14 out of 40 (35%) and 32 out of 100 cases (32%), respectively (NS); (4) the relative risk of bilateral occurrence in the FH(+) group was 1.4, with a 95% confidence interval of 0.9-2.4; (5) the 15-year survival rate was 72% and 60%, respectively, suggesting a better prognosis for the FH(+) group (P < 0.01); and (6) multivariate analysis showed that the contribution of FH to postoperative survival was marginal (P = 0.07). Factors related to the hormonal environment such as age at menarche (P = 0.08) and age at menopause (P = 0.08) made a greater but non-significant contribution to the prognosis of the FH(+) group than to that of the FH(-) group. However, further genetic and molecular biological analyses of familial breast cancer are needed in order to clarify the mechanisms of cancer accumulation within families.