To investigate the clinical and biologic significance of the circulating t(14;18)-carrying cells in follicular lymphoma (FL) patients, we analyzed the mbr/JH junction of the hybrid bcl-2/IgH gene simultaneously at the DNA and RNA levels by polymerase chain reaction (PCR) in 37 peripheral blood samples from 37 patients in different remission status: 4 before treatment, 8 during treatment, and 25 in complete remission (CR). Of these 37 patients, 22 were positive either at the DNA or RNA level (8 with active disease and 14 in CR). Among these positive patients, RNA was more often negative for patients in CR (9 of 14 [64%]) than for patients with active disease (2 of 8 [25%]; Fisher's exact test, P = .09). Among the 14 patients in CR with residual disease, 2 of 5 with RNA positivity relapsed, whereas 1 of 9 with RNA negativity and DNA positivity relapsed with a median follow-up after sample collection of 8 months (range, 4 to 18 months). Simultaneous analysis of the bcl-2/IgH gene at the DNA and RNA level showed heterogeneous patterns of PCR positivity in regards to the evaluation of the biologic activity of the t(14;18)-carrying cells. A larger study and long-term follow-up will help in determining whether the expression patterns in turn reflect the functional status of disease activity in FL patients.