Neoadjuvant chemoradiotherapy has become the standard approach for patients with locally advanced rectal adenocarcinoma. For patients who achieve a complete response determined preoperatively, less than maximally aggressive surgery has been contemplated. However, improved accuracy of the preoperative assessment needs to be established. In the current prospective evaluation, assessments of response were made with and without the use of PET/CT in a consecutive series and it was found that the additional scans were useful adjuncts to comprehensive clinical examination.