Sialyl Le(a) antigen (CA19-9), a member of a family of high molecular weight glycoproteins, was originally described as a gastrointestinal- and pancreatic-specific tumor marker. Recent studies have demonstrated that sialyl Lea is a ligand for E-selectin and may play an important role in tumor metastasis. However, expression patterns of sialyl Le(a) have not yet been established in human gallbladder carcinomas. In this study, we examined sialyl Le(a) expression in human gallbladder adenocarcinoma and its clinicopathological significance. Sialyl Le(a) immunoreactivity was detected not only in cancer cells (cytoplasmic type; 68.5%, 37/54) but also in cancer stroma (stromal type; 46.3%, 24/54). According to TNM classification, stromal sialyl Le(a) expression was detected in 60. 0% (24/40) and 7.1% (1/14) of the T2-4 and T1 cancers, respectively (p<0.01). Stromal sialyl Le(a)-positive gallbladder cancers frequently showed lymphatic invasion, venous invasion and lymph node metastasis (62.9%, 62.5% and 70.0%, respectively) (p<0.01). These observations suggested that sialyl Le(a) expression plays important roles in vascular invasion and metastasis of human gallbladder adenocarcinomas.