Mature T-cell lymphoid malignancies comprise a group of heterogeneous diseases that vary in clinicopathological features, biological behavior, treatment response, and prognosis. Bone marrow (BM) infiltration is more commonly present in mature T-cell lymphoid malignancies compared with their B-cell counterparts and hence important for differential diagnosis. In this study, clinical characteristics and prognostic factors were analyzed in 225 patients with mature T-cell lymphoid malignancies treated in a single institution. These included 29 cases of T-cell lymphoproliferative disorders (T-LPD, all with BM infiltration) and 196 cases of T-/natural-killer-cell lymphoma (T/NKCL, 56 with BM infiltration and 140 without BM infiltration). The estimated 5-year overall survival (OS) rates of T-LPD and T/NKCL were 96.6% and 37.3%, respectively. T-LPD patients were less likely to exhibit poor performance status, advanced disease stage, presence of B symptoms, or abnormal level of serum β-2 microglobulin. With similar pathological characteristics, T/NKCL patients with BM infiltration showed significantly lower response rates and shorter OS than those without BM infiltration (P = 0.0264 and P<0.0001, respectively). Multivariate analysis indicated that poor performance status, advanced disease stage, elevated serum lactate dehydrogenase level, and BM involvement were independent unfavorable prognostic factors. The Glasgow Prognostic Score may be more efficient than the International Prognostic Index in predicting disease outcome in T/NKCL. In conclusion, clinical characteristics may be useful in more effectively stratifying patients with mature T-cell lymphoid malignancies.