International Standard (IS) 13/132 is a freeze dried preparation of 0.5 mL pooled human plasma taken from 6 donors who experienced a recent Toxoplasma gondii infection. The potency of IS 13/132 was compared to ISs TOXM and 01/600 in various titrationassays and immunoassays. 13/132 was endorsed as the 4th IS for Antibodies, Human, to Toxoplasma gondii replacing the 3rd IS TOXM, with an assigned unitage of 160 IU per ampoule by dye test and an IgG content of 263 U per ampoule by immunoassay. A