In China, which is a non-endemic area for celiac disease, primary intestinal T-cell and NK-cell lymphomas might comprise heterogeneous subtypes. Both type II enteropathy-associated T-cell lymphoma and primary intestinal NK-cell lymphoma are rarely reported and poorly characterized in China. In this study, we examined the clinicopathological and molecular features of 38 cases of primary intestinal T-cell and NK-cell lymphoma in Chinese patients. Based on these findings, we first classified the patients into an NK-cell group (n=6) and a T-cell group (n=32). In the NK-cell group, the mean age was 37 years. All tumors of the NK-cell group were positive for Epstein-Barr virus encoded mRNA in the majority of tumor cells and were polyclonal according to the results of commercial BIOMED-2 T-cell receptor gene rearrangement assays. The survival in the NK-cell group was significantly worse than that of the T-cell group (P=0.0247). Next, 7 tumors of the T-cell group were considered type II enteropathy-associated T-cell lymphoma, while 24 were considered peripheral T-cell lymphoma, not otherwise specified (NOS). In the type II enteropathy-associated T-cell lymphoma group, the mean age was 55 years. Type II enteropathy-associated T-cell lymphoma tumor cells from all seven patients were monomorphic, medium sized. The survival in the type II enteropathy-associated T-cell lymphoma group was significantly worse than that of the peripheral T-cell lymphoma, NOS group (P=0.0181). Multivariate analysis identified NK-cell phenotype, male gender, and CD8 positivity as factors for poor prognosis in our series of primary intestinal T-cell and NK-cell lymphoma patients. In conclusion, most cases of primary intestinal T-cell and NK-cell lymphoma in China are not associated with celiac disease and could be classified to NK-cell group, type II enteropathy-associated T-cell lymphoma group, and peripheral T-cell lymphoma, NOS group. Each group has distinctive histopathological features with prognostic significance.