This paper is a diachronic analysis of a corpus of 180 titles drawn from CRs published in the BMJ and the BMJ Case Reports between 1840 and 2009. The frequency of occurrence of 69 variables (e.g. title type and length, punctuation, grammatical and syntactic data, number of authors and collaboration practices) was recorded for each title. The corpus was divided into three blocks (1840-1850, 1920-1930 and 2009) and between-block comparisons were carried out. Our findings show that CR titles have evolved over the 160-year period studied in the sense that they have increased in length, syntactic complexity, semantic richness and title type diversity. Authorship patterns and collaboration practices have changed, too. Although internationalization of case reporting has increased over time, today’s preferred practice is still local collaboration. The only variable that has remained constant over the years is the nominal nature of CR titles. We put forth several social and scientific factors that could account for the various shifts observed. The non-informativeness of CR titles that persisted over time can be explained by the fact that CR authors are reluctant to give a generalization flavor to their findings based on single cases.This paper forms part of a wider research that is supported by Grant M-976-09-06A from the Scientific, Technological, Humanistic and Artistic Research Center (CDCHT) from the University of The Andes, Mérida (Venezuela)