The mammographic patterns of the patients treated with conservative surgery (quadrantectomy) plus radiotherapy for early breast carcinoma were evaluated to assess treatment-induced changes over time and to improve the differential diagnosis between postirradiation effects and possible tumor recurrences. The mammographic examinations of 79 patients who had undergone quadrantectomy and radiotherapy for breast carcinoma (stage T1-T2) were examined. Skin thickening, edema, fibrosis, distortion and calcifications were considered and classified by comparing the radiographic patterns of the treated breast with those of the contralateral and untreated one. Pattern changes over time were also evaluated and quantified by comparing serial follow-up examinations of the same breast. The percentage of patients with irradiation-induced skin thickening steadily reduced from 100% at 6 months to just above 50% at 4 years. The number of patients showing diffuse irradiation-induced edema decreased from 56% at 6 months to 15% at 1 year and to 0% at 2 years, while the number of cases with localized edema decreased more slowly. The incidence of localized postirradiation breast fibrosis increased to 74% at 4 years, while diffuse fibrosis stabilized around 14%. The patients with no postoperative breast distortion accounted for nearly 33% of the examined cases, while those with minimal distortion approximated 58% and those with gross distortion 9%. In conclusion, the overall results confirmed the value of mammography in the follow-up of the patients treated with QUART.