Introduction: Primary intestinal non-Hodgkin's lymphoma is a part of extranodal non-Hodgkin's lymphoma which is rare in incidence, moreover when complicated with chylothorax.Case Report: A 26-year-old female patient was referred to our hospital presenting a distended abdomen, dyspnea, and sepsis due to infected surgical wound from a laparotomy and hemi-colectomy with ileostomy done 11 days before in other hospital. Pathology result was an intestinal activated B-cell non-Hodgkin lymphoma with positive CD20 and MUM1 immunostaining. A massive milky pleural effusion with a high level of triglycerides indicating a chylothorax was managed by insertion of water seal drainage. An R-CHOP regimen was commenced after stabilization of critical condition, and the chylothorax improved after two cycles of chemotherapy. The patient completed eight cycles of R-CHOP and achieved complete remission followed by a surgical re-anastomosis. She remained in complete remission with fully active life for almost four years until this report was submitted.