A list is presented of references to all known publications on properties which have served to relate strains of HeLa cells to each other as well as to indict other purported human cell lines as HeLa cell contaminants. Eleven additional cell lines not previously indicted are described. When they exhibit (i) type A (fast) mobility for glucose-6-phosphate dehydrogenase, (ii) phosphoglucomutase type 1 at locus 1 and locus 3, (iii) absence of a Y chromosome by fluorescent staining, and (iv) possession of a complex of trypsin-Giemsa banded marker chromosomes present in known HeLa cells, then cell substrates regardless of designation should be considered de facto strains of HeLa.