Participants with relapsed or refractory follicular lymphoma with EZH2 gene mutation will receive Tazemetostat 800 milligram (mg), tablet, orally, twice daily or as per physicians discretion in routine clinical practice. All the participants will be observed for up to Week 52 prospectively.

Tazemetostat oral tablets.

An ADR is defined as harmful and unintended responses to the normal administration/use of drugs, in which a causal relationship with the drug in question cannot be ruled out. Adverse events (AEs) with unknown causality to the drug among those voluntarily reported will be also considered ADRs.

Serious ADRs are defined as any untoward medical occurrence or effect that at any dose resulted in death or life-threatening conditions or required hospitalization or prolongation of existing hospitalization, persistent or significant disability or incapacity, congenital anomaly or birth defect or medically important condition.

Number of participants with ADRs such as myelosuppression and infection based on participants background factors will be reported. Participant background factors will be sex, age, height, weight, clinical stage (Ann Arbor classification), the presence or absence of B symptoms, Eastern Cooperative Oncology Group Performance Status (ECOG-PS), complications, past history and history of drug allergy.