Neoadjuvant treatment has shown its effectiveness in improving patient's outcome in locally advanced rectal carcinoma. Some patients show excellent response while others do not. We led a retrospective study with a rectal adenocarcinoma who had undergone initial MRI assessment and needed a neoadjuvant chemo-radiotherapy.The studied included 22 men and 8 women with a mean age of 57 years old. Eighteen patients had MRI after neoadjuvant treatment : tumoral response was considered subtle in 3 patients, almost complete in 3 patients and partial in 12 patients.Histological final assessment showed a complete response in 2 patients, partial response in 22 patients and non responsive tumor in 6 patients.Univariate analysis observed that having more than five loco regional lymph nodes, a more than 10mm suspicious loco regional lymph node and suspicious iliac lymph nodes on the initial MRI significantly increased (p=0.0001) the risk of absence of histological response. Combining conventional and functional MRI findings seems to have promising results helping the surgeon build a prediction model at the initial diagnosis and replan the treatment after the neoadjuvant chemo-radiotherapy.