The human leukocyte antigen (HLA) system is comprised of a group of genes essential to immune function. This group of genes encodes cell-surface antigen-presenting proteins on the outside of a cell, which identify the cell as a self cell or non-self cell. The immune system seeks out non-self cells for destruction. Matching HLA types reduce the risk of transplant rejection or an adverse immune response. Solid organ transplantation and allogeneic stem cell transplantation represent a common treatment for end-stage organ failure and several hematological and non-hematological malignancies. Matching the patient with an unrelated donor for HLA molecules significantly decreases the probability of graft rejection, exposure to any graft diseases, and transplant-related mortality. HLA type screening methods are categorized as low, medium, and high resolution, where sequencing-based typing (SBT) provides the highest resolution and is considered the gold standard of HLA typing.