The utility of a head position monitor (HPM) for measuring standing steadiness for possible application in studies investigating the effects of occupational exposure to neurotoxicants was evaluated. The HPM, a commercial instrument known as the NeuroTest Sway Plot Postural Sway Analyzer, was designed to measure the position of the subject's head in two dimensions using a sonic emitter attached to a lightweight headset placed on the subject and two receivers located in the same horizontal plane on a tripod placed 20 to 30 centimeters (cm) from the source. The emitter produced a series of discrete clicks at 60 millisecond (msec) intervals and its position was calculated relative to the two sensors. The click data were digitized and recorded as a series of X-Y coordinates, sampled every 60msec, by a personal computer controlled data processing system. The amount of postural sway indicated by the HPM was determined and evaluated in 118 volunteers, 60 females and 58 males, by comparing the data with those obtained by a conventional force platform, regarded as the standard device for postural sway measurements. Sway speed, defined as the total length of the sway path in centimeters divided by the time interval in seconds, was measured for each subjects. An additional 56 males were tested with the force platform only and 37 males were tested with the HPM alone. Correlations between the sway data obtained by the two devices were examined by correlational and covariance analysis techniques. Data obtained by the HPM and force platform were strongly correlated, correlation coefficients varying from 0.568 to 0.87. Intradevice correlations were also high, correlation coefficients varying from 0.75 to 0.91. A significant age/sex interaction was also seen, steadiness decreasing with increasing age in the male subjects, but not in females. The authors conclude that measures of standing steadiness obtained with the HPM appear to be similar, though not identical, to those obtained with a force platform. The HPM may be useful in field studies of the effects of occupational exposure to neurotoxicants where force platforms are difficult to use.