The role of 90K and galectin-3 in cell-to-extracellular matrix adhesion and tumor metastasis has been reported, but little is known about their role in the prognosis and extranodal involvement of diffuse large B-cell lymphomas (DLBCL). Thus, we measured serum 90K concentration by enzyme-linked immunosorbent assay and tissue expression of galectin-3 by immunohistochemistry in newly diagnosed DLBCL patients. The mean serum 90K concentration was higher in DLBCL than in healthy controls (1,408.81 ± 89.45 vs. 980.94 ± 58.69 ng/ml, p = 0.036). High serum 90K (median value ≥1,249.50 ng/ml) and high galectin-3 expression (grade 3 positive staining in >75% of cells) showed a significant association with stage III/IV, ≥2 extranodal involvements and risk of high/high-intermediate international prognostic index (p < 0.05). The complete response (CR) rate (86.9%, 20/23) in the low 90K group was higher than in the high 90K group (56.5%, 13/23). Among 14 patients with high galectin-3 expression, only 6 patients showed CR (42.9%). The time to progression and overall survival were shorter in the group with high 90K and galectin-3 expression (p < 0.05). In conclusion, serum 90K and galectin-3 expression might be useful markers to indicate the extent of lymphoma involvement and prognosis in DLBCL.