Monoclonal antibody which is an immunoglobulin G with anti-CD20 activity that contains 664 amino acids. Indicated for treatment of Rheumatoid Arthritis, Hodgkin Lymphoma and Chronic Lymphoid Leukemia. At latest update relevant data on breastfeeding were not found. Because of a high molecular weight, excretion into breast milk is very unlikely. Its low oral bioavailability makes that serum levels in the infant that could be originated from milk absorption are to be absent or scanty, except in premature infants or in the early period after birth in which gut absorption may be increased. Many reports have not shown harmful effects in the infant after long-lasting intrauterine exposure . However, despite it is thought to be safe while breastfeeding, and, until more data on this drug is available, in cases of Rheumatoid Arthritis a known safer alternative should be used.