New technologies have resulted in the ability to identify the presence of IgG human leukocyte antigen (HLA) or non-HLA antibodies in the sera of potential solid organ transplant recipients. Knowledge of the presence of these antibodies, their antigen specificities, and strength (titer) is crucial to understanding a patient's state of immunologic sensitization and reactivity. Finally, these data, when correlated with sensitive crossmatch results, allow clinicians to make more knowledgeable clinical decisions when paring donors and recipients for transplant.