<p>Titles are a critical feature of research articles (RAs) and have become increasingly vital in enhancing the visibility of RAs. However, relatively few researchers have conducted a comprehensive and fine-grained analysis to examine how medical RA titles have evolved over the past 100 years. To help bridge the gap, we tracked diachronic changes in medical RA titles in terms of length, content, formats, and syntactic structures, based on a corpus comprising 1760 titles from 1920 to 2020. Results showed that the mean title length has increased over time. Concerning title content, the mention of clinical context consistently appeared most frequently (at all the time points) and the mention of method, patient population, and treatment have significantly increased. Regarding formats, two-unit titles have risen significantly (exceeding one-unit titles since 2010), and the use of colons has shown the largest increase among six types of two-unit titles. Syntactically, the use of “uni-head nominal group” has significantly decreased (though remaining the dominant structure). These observed changing patterns of medical RA titles may be related to the advent of online search algorithms, as well as the development and professionalization of the medical discipline. Our findings have implications for scientometrics and informetrics.</p>