Retic-Chex II is an assayed, whole blood control that can be used for both manual and automated reticulocyte counting methods. The control mimics the appearance of patient samples and is available in three clinically significant levels. Its long shelf life reduces the number of shipments, associated costs and time spent performing lot-to-lot correlation. Retic-Chex II is packaged in 1.0 mL squeeze dropper vials for accurate sample dispensing, eliminating the need for manual users to pipette. Retic-Chex II is assayed for manual reticulocyte counting methods, including the Miller Disc method. It can also be used with automated hematology analyzers, including the Beckman Coulter LH 500 and HmX and Abbott CELL-DYN 3500/3700.