β-mannosidase, encoded by MANBA, has been suggested to be implicated in cancers, while genetic variations in the MANBA in relation to colorectal cancer (CRC) risk has not been examined. In this study, we investigated the relationship of a polymorphic CA repeat in MANBA gene with CRC risk in 152 Swedish CRC patients and 441 Swedish controls, and 196 Chinese CRC patients and 577 Chinese controls, as well as the clinicopathologic significance of this polymorphism on CRC patients, by using capillary electrophoresis. The MANBA genotypes were related to CRC risk in the Swedish population (p=0.03), but not in the Chinese population. In the Swedish population, individuals with < 22 CAs/> 22 CAs had significantly increased risk for CRC compared with those with ≥22 CAs/≥ 22 CAs (gender-age-adjusted analysis: OR 1.93, 95% CI 1.06-3.51). There was no relationship between the polymorphism and clinicopathologic variables. These findings suggest the different susceptibilities of this polymorphism to CRC development in the two populations. © 2008 Taylor & Francis.