In spite of the fact that penetrating trauma is an increasingly frequent cause of death and disability in America, little epidemiologic information is available on the recurrence rate or natural history of patients sustaining such injuries. The current study therefore was carried out to determine the recurrence rate of penetrating trauma in our institution. During the 12-month study period (August 1984 through July 1985), 556 (2%) of the 26,728 patients examined in our surgical emergency department had sustained penetrating trauma. After excluding patients who died at the time of their original injury and patients whose records were incomplete, 389 (70%) of the 556 patients were available for analysis. As of January 1990, 127 (32.6%) of the 389 patients had sustained two or more documented episodes of penetrating trauma. The incidence of recurrent penetrating trauma in the patients treated and released from the emergency department (35%) was similar to that of the patients requiring admission for their index injuries (31%). Based on the fact that the incidence of recurrent trauma was highest in men (p less than 0.01), blacks (p less than 0.01), and the uninsured (p = 0.03), it appears that recurrent penetrating trauma is a major societal as well as a medical problem.