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 correlated with known clinical or pathological variables, including tumor stage, grade or extramural vascular invasion.Furthermore, nuclear p27kip1 expression had no impact on survival. However, we identified a significant correlation 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 improved patient survival (P = 0.059).CONCLUSION: These findings support the recent evidence that cytoplasmic p27kip1 has a distinct and imporrant biological role that can influence tumor outcome.