OBJECTIVES To evaluate and compare trends in design characteristics of brief-summary formats of prescription drug print ads. METHODS The source for these ads include a consumer magazine - National Geographic (NG) and three medical journals – Annals of Internal Medicine (AIM), The Journal of the American Medical Association (JAMA) and The New England Journal of Medicine (NEJM). Each source was visually reviewed by research assistants to record information from brief summaries on ads from issues dated January 1, 2000 through December 31, 2004. The design characteristics evaluated were text font size, font consistency, presence of bullets, highlights, tables, graphs, format type (e.g.: question/answer format), warning box, spacing between lines, and number of columns used to present the material. Font size was measured using the Compugraphic scale. Data were coded and analyzed using SAS® 9.1. Descriptive statistics and comparisons using chi-square tests were performed to evaluate differences by year and source at a priori significance level of 0.05. RESULTS A total of 7266 printed ads for 240 products manufactured by 90 pharmaceutical companies were evaluated from NG (95), AIM (1372), JAMA (1787), and NEJM (4012) respectively. There were significant differences (p<0.05) in most design characteristics by year (2000-2004), namely font consistency, presence of bullets, highlights, tables, graphs, and warning box. These differences were also statistically significant (p<0.05) across sources (magazine/journals). The question/answer format and presence of a warning box was mostly seen in ads obtained from the magazine. The mean (SD) font size of the text on these ads was small (5.7 ±1.1) and consistent throughout these ads by year and source. CONCLUSIONS Prescription drug print ads have changed over the years and are different based on the readership source. Further improvement in standardizing the format and increasing the text font may help the intended readers of these ads.