Anti-lymphocyte globulin (ALG) is an infusion of horse-derived antibodies against human T cells which is used in the treatment of acute rejection in organ transplantation, especially in kidney transplants.

It is less commonly used than the similar anti-thymocyte globulin (ATG), and like ATG it is associated with cytokine release syndrome in the short term and an increased risk of post-transplant lymphoproliferative disorder in the long term. ALG is more likely to cause side effects than ATG, but is safer than OKT3.

At one point in the mid 1990s, the world's entire supply of ALG came from a horse called Volcano, who lived in South America.