Therapeutic antibodies have been increasingly used for the treatment of various diseases, including cancers and chronic inflammatory diseases. The pharmacokinetic interindividual variability of mAbs is large and influences, at least in part, the clinical response to antibody treatment. This variability is explained by a number of individual sources of variability, which are reviewed here. Some of them are major because they are frequently reported to greatly influence the interindividual variability; notably, increased body size, the presence of anti-drug antibodies, and high antigen mass are associated with decreased antibody concentrations. Other individual sources of variability are of less critical importance. They include sex, age, co-treatments, or genetic polymorphisms of IgG Fc receptors (FcgRs). The interindividual variability of antibody pharmacokinetics should be soundly described in order to design optimal dosing strategy.