Of the total of 137 cultured cell lines from a wide variety of human neoplasms now typed at a maximum of 16 of their polymorphic enzyme loci, the phenotype combinations for 72 are described in this paper. The phenotype frequency product of each line was less than 0.05, and only 148 of the 9,316 (1.6%) pairwise comparisons between lines had phenotypes that did not differ in at least one locus. Thus the probability of any two randomly selected lines having indistinguishable genetic signatures in this sample of 137 lines was 0.016. Fifty-two of the 137 lines (38%) had phenotype combinations distinguishable from each of the other 136 lines. The frequency products of the 85 lines that could not be distinguished from at least one other line were all sufficiently high to preclude a suspicion that contamination had occurred among them. No additional cell lines with phenotype combinations indistinguishable from the combination characteristic of HeLa cells were identified among these 72 cell lines.