The International Prognostic Index (IPI) and Follicular Lymphoma Prognostic Index (FLIPI) are used as prognostic indices for NHL and indolent lymphoma. However, marginal zone B-cell lymphoma (MZL) evidences a distinctive clinical presentation and a natural course; thus, in this study, we attempted to devise an adequate prognostic index for MZL. Two-hundred and five patients diagnosed with MZL were retrospectively reviewed. After analysis of the prognostic factors, progression-free survival (PFS), and overall survival (OS), we constructed a prognostic index of MZL (MZLPI) via the summation of each factor. We then compared PFS and OS with IPI, FLIPI, and MZLPI. According to our multivariate analysis, nodal MZL, ECOG performance > or = 2, and advanced stage were composed of MZLPI. MZLPI was grouped as follows: score 0 as a low-risk group, score 1 as an intermediate risk group, and score 2 as a high-risk group. The PFS curve, according to MZLPI results, evidenced a more discriminated pattern than IPI and FLIPI, and this was especially true in the intermediate risk group. In OS, MZLPI (P=0.0007) evidenced a more discriminated pattern than IPI (P=NS) or FLIPI (P=0.0044). MZLPI, which is constructed of relatively simple factors, may represent a useful prognostic index for the prediction of PFS and OS in MZL, and may also be used as a substitute for IPI or FLIPI.