We analyzed lymphocyte morphology, histology, immunophenotype, immunoglobulin heavy chain (IgV_H) gene mutations, and clinical course in 80 unselected patients presenting with circulating t(11;14) lymphocytes. Of the 80 patients, 43 had peripheral lymphadenopathy (nodal group), and histology confirmed mantle cell lymphoma (MCL) in all. There were 37 patients with no lymphadenopathy (nonnodal group); 13 of 37 had histology, all showing MCL. IgV_H genes were unmutated in 28 (90%) of 31 nodal and 15 (44%) of 34 nonnodal cases (P = .0001); CD38 was positive in 32 (94%) of 34 nodal and 16 (48%) of 33 nonnodal cases (P < .001); 41 (95%) of 43 nodal patients required immediate treatment compared with 18 (49%) of 37 nonnodal patients who had indolent disease (P < .0001). Median survival (95% confidence interval) was 30 months (10-50) in the nodal group and 79 months (22-136) in the nonnodal group (P = .005). Mutation status did not statistically affect survival, but of 6 long-term survivors (> 90 months) all were nonnodal and 5 of 5 had mutated IgV_H genes. Lymphocyte morphology was heterogeneous in both groups: typical MCL in 56 cases (34 nodal, 22 nonnodal), blastoid MCL in 8 cases (3 nodal, 5 nonnodal), and small-cell MCL in 16 cases (6 nodal, 10 nonnodal, P = .12). Matutes immunophenotyping score was 1 in 65 cases and 2 in 15 (8 nodal, 7 nonnodal). We find no evidence against a diagnosis of MCL in the nonnodal group and suggest that mutated IgV_H genes may help identify patients with indolent disease.