Purpose.To determine how many ultrasound pachymetry measurements are required to obtain a reasonable estimate of central corneal thickness.Methods.Five central corneal thickness measurements were obtained from each eye of 101 patients with normal corneas. The means of fewer than five readings were compared with the mean of five values for each eye to determine the incremental clinical value of additional measurements.Results.Compared with the mean of five values, fewer than three measurements per eye provided a mean central corneal thickness value with inadequate confidence. Conversely, means of more than three readings provided little additional confidence over means of three values.Conclusions.Central corneal thickness by ultrasound pachymetry can be adequately assessed in the majority of eyes by taking three measurements per eye.