AIM: To evaluate the prognostic significance of p27kip1 in colorectal cancer patients. METHODS: Cytoplasmic and nuclear p27kip1 expression was evaluated in 418 colorectal cancers using tissue microarrays. Data were associated with known patient and tumor variables and long-term patient outcomes, providing further insight into the mechanisms by which p27kip1 may influence tumor development. RESULTS: Nuclear and cytoplasmic p27Kip1 expressions were detected in 59% and 19% of tumors respectively. Cytoplasmic p27Kip1 was almost invariably associated with positive nuclear p27Kip1 expression. Neither case correlat- ed with known clinical or pathological variables, includ- ing tumor stage, grade or extramural vascular invasion. Furthermore, nuclear p27kip1 expression had no impact on survival. However, we identified a significant correla- tion between expression of cytoplasmic p27kip1 and longer disease-specific survival times. On multivariate analysis, TNM stage and extramural vascular invasion were highly significant independent prognostic factors, with positive cytoplasmic p27 expression showing a trend towards im- proved patient survival (P = 0.059).CONCLUSION: These findings support the recent evi- dence that cytoplasmic p27kip1 has a distinct and impor- tant biological role that can influence tumor outcome. METHODS: The expression of Cytoplasmic and nuclear p27kip1 was evaluated in 418 colorectal cancers using tissue microarrays. Data were associated with known patient and tumor variables and long-term patient outcomes, providing further insight Into the mechanisms by which p27kip1 may influence tumor development. Cytoplasmic p27Kip1 was almost invariably associated with positive nuclear p27Kip1 expression. Neither case correlat- ed with known clinical or, pathological variables, includ- ing tumor stages, grade or extramural vascular invasion. However, we identified a significant correla tion between the expression of cytoplasmic p27kip1 and longer disease-specific survival times. On multivariate analysis, TNM stage and extramural vascular invas ion were highly significant independent prognostic factors, with positive cytoplasmic p27 expression showing a trend towards im- proved patient survival (P = 0.059) .CONCLUSION: These findings support the recent evi- dence that cytoplasmic p27kip1 has a distinct and impor- tant biological role that can influence tumor outcome