Neoadjuvant chemoradiation therapy is one of the standard therapeutic regimens for rectal carcinoma. Nevertheless, chemoradiation therapy is not completely devoid of adverse effects, and it would be interesting to try to predict which patient will respond to neoadjuvancy. This study aimed at analyzing factors influencing pathological response after therapy. We reviewed the clinical and morphological data of 39 patients after neoadjuvant chemoradiation therapy. We performed immunohistochemistry for p53, cyclin D1, MIB-1 (Ki67), and bcl-2 protein in paraffin-embedded tissue. In our series, 12 patients did not respond to neoadjuvant therapy, 12 showed a complete response, and 15 a partial response. There was a statistically significant association between response and cardiomyopathy (p=0.02) and tenesmus (p=0.02) and a trend towards significance for age (p=0.08), preoperative TNM (p=0.08), peritumoral inflammatory response (p=0.07), and preoperative CEA (p=0.08). As for immunohistochemistry, we only found a trend towards significance for cyclin D1 (p=0.08). In our series of patients with rectal carcinoma receiving preoperative chemoradiation therapy, few factors were predictive of a histological response. The histological response seems to improve survival and reduce relapses.