The association between angiogenin and cancer progression and poor outcome in solid tumors has been documented, but its significance in leukemias has not been evaluated. Using an ELISA technique (Quantikine Human Angiogenin Immunoassay; R&D Systems), we measured serum angiogenin levels in 77 previously untreated Binet stage A B-cell chronic lymphocytic leukemia (CLL) patients. No difference in angiogenin serum levels could be found between patients (median: 295 ng/mL; range: 74-1700) and 15 age- and sex-matched healthy controls (median: 264 ng/mL; range: 29-1835) (P = NS; Mann-Whitney test). Increased angiogenin serum level was associated with higher LDH (P = 0.03) and beta2-m (P = 0.007) concentrations. However, angiogenin did not reflect the extent of bone marrow (BM) angiogenesis as evaluated by microvessel area (P = 0.611), circulating levels of vascular endothelial growth factor (VEGF) (P = 0.873) and basic fibroblastic growth factor (FGF-2) (P = 0.421). When the 25 patients with available data were stratified into the four major cytogenetic categories (normal karyotype, 13q as a sole aberration, 12q trisomy, 11q or 17p deletion) and aberrations were compared with angiogenin serum levels, no correlation was found (P = 0.651; Kruskall-Wallis test). A cut-off of angiogenin serum level corresponding to median (i.e. 330 ng/mL) or higher identified later upstaging and longer progression-free survival (PFS). The 5-yr PFS was 51.5% for patients with angiogenin levels lower than median and 85% for patients with higher values [P = 0.03; hazard ratio (HR) = 2.86; 95% CI: 1.08-6.72]. Although in multivariate analysis only Rai substages (P = 0.00001) and peripheral blood lymphocytosis (P = 0.009) retained their prognostic significance, angiogenin could be incorporated into the Rai substages thus leading to the identification of the following risk categories: (i) stage 0 (angionenin >330 ng/mL); (ii) stage 0 (angiogenin <330 ng/mL) + stage I-II (angiogenin >330 ng/mL); and (iii) stage I-II (angiogenin <330 ng/mL). The 40-month PFS were as follows: 85%, 65%, 25% (chi(2) for trend = 6.33; d.f. = 1; P = 0.01). In conclusion, serum angiogenin levels although not increased in comparison with healthy controls, may predict clinical outcome of patients with early CLL and help to refine Rai's stratification.