The objectives of this study were to estimate the incidence and identify the temporal patterns of visits to Rhode Island emergency departments (EDs) by adults who were sexually assaulted. Visits to all Rhode Island EDs from January 1995-June 2001 by adults who were sexually assaulted were identified using International Classification of Disease, Ninth Revision, Clinical Modification (ICD-9) codes. Medical records of these visits were reviewed. Frequency distributions of the assault characteristics and patient demographics were generated. Incidence rates (IRs) of ED visits after sexual assault were estimated using 2000 US Census data. Analyses of the temporal patterns of the ED visits after sexual assault were conducted. Of the 823 ED visits, 796 (96.7%) were by females and 27 (3.3%) were by males. The median age for females was 25 years (range, 18-96 years) and was 28 years (range, 18-87 years) for males. Among the female patients, 76.6% sustained a vaginal/anal assault. Among the male patients, 59.3% sustained an anal assault. The average annual IR of ED visits after sexual assault was 30.3/100,000/year for females and 1.2/100,000/year for males, which is a 25-fold greater incidence of these visits for females than males. ED visits after adult sexual assault were more frequent during warmer months and around 5 P.M. There was a gradual 43% increase in the IRs of ED visits after sexual assault over the 6.5-year period. These findings should help direct EDs to maximize supportive services when they are needed most often.