Calumenin is a multiple EF-hand Ca2+-binding protein located in the endo/sarcoplasmic reticulum of mammalian hearts. Calumenin belongs to the CREC family of Ca2+-binding proteins having multiple EF-hands. Ca2+ homeostasis in the sarcoplasmic reticulum (SR) of mammalian hearts is maintained by RyR2, SERCA2 and other associated SR resident proteins. Evidence suggests that calumenin interacts with RyR2 and SERCA2, and therefore changes in the expression of calumenin could alter Ca2+ cycling in mouse heart. In this review, current knowledge of the biochemical and functional roles of calumenin in mouse heart is described.