OBJECTIVE: Cost utility analysis (CUA) first entered the literature in the 1970s and is now considered the standard for examining the cost-effectiveness of health related interventions. This study considers CUA as a methodological innovation and traces its diffusion through the medically related literature for twenty-five years. METHODS: We used the bibliography compiled at the Harvard School of Public Health (http://www.hsph.harvard.edu/cearegistry/). All articles are original CUAs indexed in MEDLINE and other electronic databases from 1976 to 2001. For each article, we identified clinical area, journal title and type (methods, general medicine, medical specialty, and other specialty). Medical specialty refers to those fields considered subspecialties of medicine, such as cardiology and gastroenterology, while other specialties include fields such as radiology, surgery, nursing and pharmacology. We examined dissemination patterns of CUAs, and whether we could trace their spread through the literature over time. RESULTS: The number of CUAs (n = 539) plotted against year of publication yielded an S-shaped curve, matching the classic diffusion pattern seen for other innovations. Moreover, CUAs have diffused over time from general medical journals and methodological journals into a wide variety of specialty journals, tracing the typical pattern of dissemination and adoption seen for other innovations. In summary, for journal types methods, general medicine, medical specialty, and other specialty, respectively, distribution of published CUAs changed from 29%, 57%, 14%, and 0% during 1976-1984 to 14%, 29%, 37%, and 20% during 1998-2001 with transitional values in intervening time periods. CONCLUSIONS: The spread of CUAs through the literature follows patterns commonly seen in the diffusion of innovations. It is important to note that diffusion does not equal implementation. Further study is required to determine whether the diffusion of CUA has been accompanied by increasing use for decision making in clinical practice or health policy.