This study was designed to provide statistical estimates of the effects of N2O on pain and anxiety associated with tooth-pulp shock in a clinical and in a laboratory setting. Amounts of electric stimulation needed to first feel sensation, amounts to feel pain, and pain tolerance were measured. N2O had a significant effect on raising levels of absolute sensation, pain threshold, and pain tolerance in response to increasing electrical stimulation of teeth. These effects were noted when N2O and pulp stimulation were delivered in a clinical dental setting or in a pain-research laboratory. Subjects also decreased their evaluation of the intensity of the same stimulus as N2O was inhaled at various concentrations; their aversion to the same stimulus tended to be influenced by N2O to a greater extent than perceived intensity. Anxiety levels were reduced to a statistically significant degree.