In "The Effect of Low-Frequency Electrical Fields on Osteogenesis" (74-A: 920-929, July 1992), by McLeod and Rubin, in the last paragraph of the left column on page 925, the second and third sentences should read: "A flux ramp of 0.55 tesla per second and 380-microsecond duration. repeated at a rate of seventy-five hertz. was used to produce the wave-form of the pulsed electrical field (Fig. 2-A). This produced a peak electrical field in the tissue estimated to be no more than 0.1 millivolt per centimeter, as determined from the mean cortical area of all thirty-five intact ulnae that were measured (60.9 1.1 square millimeters [mean and standard error of the mean]) and the cross-sectional areas of the wings21."