This 2 stage study will compare the pharmacokinetics and safety profile of subcutaneous and intravenous rituximab in participants with follicular lymphoma. In the first stage, participants who have achieved at least a partial response after induction treatment with intravenous rituximab will be randomized to one of 3 treatment cohorts, to receive rituximab 375 milligram per square meter (mg/m^2) intravenously, 375 mg/m^2 subcutaneously or 625 mg/m^2 subcutaneously, and pharmacokinetics evaluated on an ongoing basis. Upon selection of the subcutaneous dose (800 mg/m^2) which results in rituximab trough plasma concentration (C trough) values comparable to those achieved with the intravenous formulation, participants in the second stage of the study will be randomized to receive either the subcutaneous or intravenous formulation to demonstrate comparability of the C trough levels with both routes of administration. Maintenance therapy will continue every 2 or 3 months with the subcutaneous formulation.

Inclusion Criteria:

• CD20-positive follicular non-Hodgkin's lymphoma (NHL)
• Documented partial or complete response a the end of induction treatment with rituximab
• Must have completed induction treatment, and received at least 1 dose of intravenous rituximab maintenance treatment
• Eastern Cooperative Oncology Group (ECOG) performance status of less than and equal to (<=) 2
• Life expectancy of greater than and equal to (>=) 6 months

Exclusion Criteria:

• Histological evidence of transformation of NHL, or types of NHL other than follicular lymphoma
• Presence or history of central nervous system disease
• History of malignancy other than follicular NHL
• Recent major surgery (within 4 weeks prior to screening), excluding lymph node biopsy