Blood pressure values were evaluated in 30 acute adult trauma patients using two indirect methods, the bell and diaphragm components of the stethoscope, and one direct arterial method. K1, K4, and K5 measurements were taken 4 to 72 hours (M = 30) after admission when vital signs had stabilized. Data were collected using a random-zero (RZ) sphygmomanometer for indirect blood pressure and radial intraarterial cannula for direct blood pressure. The sequence of measurement was randomized and variables shown to alter blood pressure values were controlled. There was no overall significant difference in K1, K4, and K5 blood pressures among the three methods. These results suggest that when clinicians monitor variables such as the frequency response of arterial lines and peripheral vascular resistance, indirect blood pressure methods are reliable for use with stabilized trauma patients.