The role of advanced trauma life support (ATLS) in the prehospital care of the critically injured is highly controversial. This study analyzes the efficacy of ATLS in the management of critical penetrating wounds of the thorax and abdomen. In the 2 1/2-year period ending July 1984, 203 consecutive patients underwent emergency laparotomy or thoracotomy for gunshot and stab wounds. All patients were treated in the field by advanced paramedics (EMT-P). For gunshot wounds the mean time (+/- S.E.M.) responding to the scene was 4.5 (+/- 0.29) minutes, on the scene 10.1 (+/- 0.41) minutes, and returning to the hospital 6.4 (+/- 0.32) minutes. For stab wounds the mean time responding to the scene was 4.8 (+/- 0.21) minutes, on the scene 9.5 (+/- 0.37) minutes, and returning to the hospital 5.7 (+ 0.30) minutes. The number of intravenous lines started averaged 1.8 per patient. Eighty-one patients had PASG applied and 28 patients underwent endotracheal intubation (21 orally, seven nasally). Thirty-three patients had no obtainable blood pressure, of whom six survived (18%). One hundred sixty (94%) of the remaining 170 patients who had any initial blood pressure survived. One hundred nine (55%) patients had an increase in BP greater than or equal to 10 mm Hg (average, 35.6 mm Hg), 64 (32%) had no significant change, and 25 (13%) had a fall greater than or equal to 10 mm Hg (average, 24.2 mm Hg) from the field to the emergency department. Twenty (80%) of the 25 patients with a fall in blood pressure survived.(ABSTRACT TRUNCATED AT 250 WORDS)