Thirty-five women whose breast cancer had been treated by radiation and 111 in whom it had not underwent unilateral breast reconstruction with the tissue expansion technique after modified radical mastectomy. Their records were reviewed and in a questionnaire the patients reported their own opinion on the results. The two groups differed significantly, because those patients who had been irradiated had a more painful course of expansion and a less over-expansion. Their reconstructed breasts were harder, had more deformities, and they required significantly more capsulotomies. The irradiated group also reported less satisfaction with the cosmetic results and more unfulfilled expectations. Tissue expansion cannot therefore be recommended as a routine procedure for breast reconstruction in patients after irradiation. However, our results do not show whether other methods are better for these patients.