Mammalian Kiaa1211 and Kiaa1211-like are a homologous pair of uncharacterized, highly conserved genes cloned from fetal and adult brain cDNA libraries. Herein we map the in utero spatiotemporal expression of mKiaa1211 and mKiaa1211L mRNA and their expression patterns in postnatal testis, skin, gastrointestinal, and adipose progenitor tissues. Significantly, mKiaa1211 is present throughout the early stages of mouse heart development, particularly in the second heart field (SHF) lineage as it differentiates from mesenchymal cells into cardiomyocytes. We also show that mKiaa1211 is expressed within several early neuronal tissues destined to give rise to central, peripheral, and sympathetic nervous system structures. Expression profiling revealed that the paralog mKiaa1211L is not expressed during the normal developmental process and that mKiaa1211 expression was noticeably absent from most adult terminally differentiated tissues. Finally, we confirm that a previously uncharacterized CRISPR/CAS-generated mKiaa1211 mouse mutant allele is hypomorphic.