The objective of this study was to investigate the influence of pregnancy in breast cancer prognosis of women under the age of 35 years. Two hundred and forty-three women with breast cancer, from three oncology departments in Athens, were investigated. Twenty-one got pregnant (7.91%) 7-100 months after breast cancer diagnosis and in a median time period of 31 months. All women had mastectomy apart from 2 who had only lumpectomy as surgical procedure. Thirteen of 21 were treated with radiotherapy and 17 of 21 had also adjuvant chemotherapy mainly with CMF for 6 cycles. Sixteen children from 14 mothers were born and the rest of the patients underwent an abortion between the 2nd and 5th month of pregnancy. All children were healthy and grew up normally up to the age of 12-142 months (end of the study) and their median age of 51 months. Only 2 patients had stage III disease at diagnosis while the remaining 19 had stage I-IIb. Three cancer recurrences were observed (14.3%) after 7-84 months. One patient had a second primary-ovarian cancer 60 months after mastectomy. Recurrence rate and survival compared with those of nonpregnant women of the same age and the stages of disease were not different. To conclude: the present study indicates that healthy offsprings can be delivered from breast cancer patients, and pregnancy does not seem to play any role in tumor recurrence.