BACKGROUND: Rectal cancer requires surgery for cure. Partial mesorectal excision (PME) is suggested for tumours in the upper rectum and implies transection of the mesorectum perpendicular to the bowel a minimum of 5 cm below the tumour. Reports have shown distal mesorectal tumour spread of up to 5 cm from the primary tumour; therefore, guidelines for cancer of the upper rectum recommend PME with a distal resection margin (DRM) of at least 5 cm or total mesorectal excision (TME). PME exerts a hazard of removing less than 5 cm - leaving microscopic tumour cells that have spread in the mesorectum. Studies at our department have shown inadequate DRM in 75 % of the patients estimated by post-operative MRI of the pelvis and by measurements of the histopathological specimen. Correspondingly, a higher rate of local recurrence in patients surgically treated with PME for rectal cancer - compared to TME - has been reported. AIM: To estimate the length of the DRM by MRI of the surgical specimen from patients operated for rectal cancer with PME. METHODS: Rectal PME-specimens will undergo MRI immediately after surgery (fresh specimen) and once more after pathological fixation (fixed specimen). Normal procedures for handling, pathological examination and reporting are completed according to international guidelines. Length of DRM measured on MR-imaging and by pathological examination will be compared. PERSPECTIVE: PME for cancer of the upper rectum may be associated with suboptimal surgery. Knowledge of the exact morphometrics in the mesorectal- and tumour surrounding tissues after surgery and pathological fixation will help to improve the surgical quality of PME for rectal cancer.