Original articlesWords Matter Sex and Gender as Unique Variables in ResearchBlakeman, John R. MSN, RN, PCCN-KAuthor Information School of Nursing, Millikin University, Decatur, and Mennonite College of Nursing, Illinois State University, Normal, Illinois. Correspondence: John R. Blakeman, MSN, RN, PCCN-K, School of Nursing, Millikin University, 1184 W. Main St, Decatur, IL 62522 (firstname.lastname@example.org). I would like to acknowledge my colleagues Sheryl J. Samuelson, PhD, RN, Sheila Jesek-Hale, PhD, RN, Kathy J. Booker, PhD, RN, and Nancy Curtin, PhD, for their critical review of this article. Their diverse experiences, perspectives, and ideas have helped me to improve this article and further develop my thinking. The author has disclosed that he has no significant relationships with, or financial interest in, any commercial companies pertaining to this article. Advances in Nursing Science: July/September 2020 - Volume 43 - Issue 3 - p 214-227 doi: 10.1097/ANS.0000000000000295 Buy Take the CE Test Metrics Abstract Sex and gender are not equivalent concepts, even though these 2 variables are often used interchangeably by researchers. The precise use of variables is critical to ensure that research and theoretical work is of the highest quality. This article defines sex and gender and the importance of recognizing both of these variables as being unique and then demonstrates the benefit of measuring both of these variables using the cardiovascular disease literature as an exemplar. Additionally, recommendations for scholars regarding the use of sex and gender in the research and theoretical literature are provided. © 2020 Wolters Kluwer Health, Inc. All rights reserved.