The TMEM16 protein family has recently been identified through several different experimental strategies including bioinformatic and microarray-based approaches. In mice and humans, there exist 10 paralogs with each containing eight putative transmembrane domains and a conserved C-terminal domain of unknown function. Mutation of at least one member of this family is associated with a human disorder, and several members of this gene family are overexpressed in different types of cancer. Despite their apparent relevance to normal development and disease, little is known about the expression of TMEM16 paralogs during embryonic development. Here, we provide a phylogenetic analysis of mouse and human TMEM16 paralogs and report the expression of Tmem16a, Tmem16b, Tmem16c, Tmem16f, Tmem16h, Tmem16j, and Tmem16k during murine embryogenesis with an emphasis on the respiratory, digestive, skeletal, and integumentary systems. These data should encourage investigations into the functions of TMEM16 paralogs in vertebrate development. Developmental Dynamics 237:2566–2574, 2008. © 2008 Wiley-Liss, Inc.