The computed tomographic (CT) scans of patients with breast carcinoma treated by surgery with and without radiation therapy were reviewed and correlated with clinical status. The optimal techniques of patient examination and the post-therapy findings were analyzed. The brachial injection of intravenous contrast material produced significant artifacts that limited interpretation of the ipsilateral chest wall in all cases and did not give additional information. Scans obtained with the patients' arms placed at their sides resulted in more clearly interpretable scans, especially when arm weakness or lymphedema precluded symmetric elevation of the arms out of the CT gantry. Radiation therapy produced both acute and chronic changes with characteristic CT appearances. The postoperative anatomy varied markedly depending on the previous surgery. Careful clinical correlation with referring physicians was the key to proper scan evaluation.