This issue of Clinics in Laboratory Medicine, guest edited by Dr. Vinay Subhash Mahajan, will focus on Immunology Laboratory Testing. Topics include, but are not limited to, Analysis of proteins and immunoglobulins in the clinical immunology laboratory; Antinuclear antibody tests; Serological diagnosis of rheumatoid arthritis; ANCA; Anti-phospholipid antibodies; Diagnostic pitfalls in autoantibody testing; Analysis of the complement pathway; Flow cytometric analysis of immune cell subsets; Testing of cellular immune function in immunodeficiencies; Food allergy testing; Evaluation of the immune response in transplantation; Laboratory testing in the context of biologics and cellular therapies; Testing immune-related adverse-events in cancer immunotherapy; Molecular diagnosis of inherited immune disorders; and Future of immunology lab testing.