Clinicians and staff are encouraged to speak up about safety concerns as a part of patient safety culture. This review had two aims: to review the literature on speaking up for patient safety, and to develop a single definition of "speaking up" in healthcare. 294 articles were identified with 51 directly focused on speaking up and the remaining on other aspects such as communication. 11 distinct definitions were identified from which the authors developed a single definition: a healthcare professional identifying a concern that might impact patient safety and using his or her voice to raise the concern to someone with the power to address it.