The aim of this study was to quantify changes in the national contributions to research related to posttraumatic stress disorder (PTSD) from 1983 through 2002. Using the Web of Science database (Thomson Scientific, Philadelphia, PA), we classified articles according to the year of publication and the country of the authors. The number of publishing countries increased from 7 between 1983 and 1987 to 39 between 1998 and 2002. Meanwhile, the U.S. output share declined from 87.6% in the first period to 62.4%. Although the number of countries publishing on PTSD has steadily increased, research is still dominated qualitatively and quantitatively by developed countries. These findings suggest a growing international acceptance of this diagnostic category. However, the immaturity of PTSD research is demonstrated by the concentration of publications in a few countries.