CD-Chex Plus is a positive procedural control for monitoring immunophenotyping by flow cytometry. It provides 30 assayed parameters including T-lymphocytes, B-lymphocytes, granulocytes, monocytes and NK cells. It is available in two clinically relevant levels of CD4+ cells and is assayed for a normal level of CD34+ cells. Designed to mimic a patient sample, CD-Chex Plus is manufactured from normal human peripheral blood leukocytes and erythrocytes. The whole blood control offers 30-day open-vial stability, eliminating the need to track thermal openings. Its long shelf life reduces the number of shipments, associated costs and time spent performing lot-to-lot correlation. CD-Chex Plus and CD-Chex Plus CD4 Low are available in cap pierceable plastic vials for use with automated flow cytometry sample preparation instruments, reducing errors and improving laboratory workflow. It is a positive procedural control designed to verify the accuracy and reproducibility of the steps involved in the process of the immunophenotyping including reagent staining, erythrocyte lysis, sample preparation, and instrument performance. CD-Chex Plus is compatible with BD Biosciences and Beckman Coulter flow cytometry systems.