Objective: Loss of Raf-1 Kinase Inhibitor Protein (RKIP) expression has been implicated in disease progression in several tumor types. The aim of this study was to evaluate RKIP expression in colorectal cancer stratified by histological "zones" and to determine the zone responsible for its clinical relevance. Method: Immunohistochemical expression of RKIP was assessed in 100 colorectal cancers using whole tissue sections. Four different areas were evaluated using 10 highpower-fields (HPFs) each: normal mucosa, tumor center, invasion front and tumor buds. The average expression for each zone was assessed for its clinical relevance. Results: Expression of RKIP was diffuse in normal mucosa and progressively lost towards the tumor center and front (26 %, 15 % and 8 % RKIP-positivity, respectively; p<0.0001). Only 3 % of tumor buds were RKIP-positive. RKIP loss in the tumor center only corresponded to more frequent lymph node positivity (p=0.0766), distant metastases (p=0.0243), lymphatic invasion (p=0.0533) and more advanced TNM stage (p=0.0278). RKIP loss was highly prognostic (HR (95 % CI): 0.45 (0.2-0.9); p=0.0288) independently of TNM and therapy. Conclusion: The clinical relevance of RKIP is restricted to the tumor center where it acts as an independent prognostic factor. Its absence in tumor buds provides further evidence to support their hypothesized metastatic potential.