Despite various weaknesses, the impact factor (IF) is still used as an important indictor for scientific quality in specific subject categories. In the current study, the IFs of rheumatology journals over the past 10 years were serially analyzed and compared with that from other fields. For the past 10 years (1999-2008), the IFs published by the Institute for Scientific Information in the Science Citation Index-Journal Citation Report were analyzed. For the majority of rheumatology journals, the IF shows a gradually increasing trend. The mean and median level of increase of IF from 1999 to 2008 is 233.9 and 66.5%, respectively. The increase in IF from 1999 or the first year with IF documentation to that in 2008 was higher for European journals than for the USA journals. The aggregate IF and the median IF of rheumatology journals remained within the top 30% and top 15% in clinical medical and all the scientific categories, respectively. Over the past 10 years, rheumatology journals showed a general increase in IF and rheumatology remained a leading discipline. For journals in the English language, those from Europe had an even higher increase than those from USA.