The Zwislocki theory of temporal summation was tested for vibrotactile sensitivity. Vibrotactile thresholds were determined as a function of pulse repetition rate and pulse number for short pulses. Thresholds for various burst durations of sinusoidal signals were also determined. The results indicate that the theory is sufficient to predict vibrotactile thresholds for the temporal patterns used. An earlier finding, which suggested that glabrous skin contains at least two populations of mechanoreceptors, was confirmed by using contactors of varying size.