The deletion of chromosome 11q is observed frequently in tumors of the large intestine. To investigate the relationship between aberrations of chromosome 11 and histopathological features of colorectal carcinoma, we examined the frequency of chromosome aberrations using fluorescence in situ hybridization to 29 short-term cultured cells from surgical specimens. Numerical aberrations were not related to any factors. The deletion of chromosome 11 was frequently observed in larger (> or = 5 cm) and more invasive tumors (> or = T3 category) (p < 0.05). Furthermore, the incidence of aberrations tended to increase in Dukes' B. Although translocation of chromosome 11 was also found in 17% of cases, it was not associated with histopathological features. Our findings indicate that the deletion of chromosome 11 is closely related to the progression of colorectal carcinoma.