AbstractFrom HeLa and its multiple identities, to MDA‐MB‐435, erroneously and widely used as breast cancer cells, the history of cancer cell lines is rich in misidentification and cross‐contamination events. Despite the fact that these problems were regularly signaled during the last decades, many actors of research still seem to ignore them. A never‐ending story? Solutions exist, notably based on recent technical advances in cell line authentication (short tandem repeat analysis). However, a collaborative action involving users of cell lines, cell banks, journals and funding agencies is needed to achieve success. © 2007 Wiley‐Liss, Inc.