The functional intronless gene coding for a calmodulin-like protein (CLP) has been localized to human chromosome 10p13-ter. Chromosomal assignment was performed by Southern blot analysis of DNA from human-rodent somatic cell hybrids and amplification of a CLP gene-specific 1090-bp DNA fragment by the polymerase chain reaction (PCR) on DNA from human-hamster cell hybrids. Chromosomal sublocalization was carried out by in situ hybridization of human chromosome metaphase spreads. The CLP gene is the first member of the human calmodulin/calmodulin-like gene family to be chromosomally sublocalized. Its presence near the telomeric end of the short arm of chromosome 10 may be of significance with respect to its highly (epithelial) cell-type restricted expression in vivo and strong downregulation upon malignant transformation. The generation of a human CLP gene-specific sequence tag site specified by the two primers used for PCR should prove useful for future linkage studies.