The masking of vibrotactile signals delivered to the index fingertip was measured as a function of the intensity of the masker, which was administered to the thenar eminence of the same hand. Combinations of test and masker frequencies were used so that the two signals would occur within the response ranges of the Pacinian and non-Pacinian mechanoreceptor systems. When the frequencies of both masker and test signal were within the range of either system (within channel), masking was effective. A 300-Hz masker (Pacinian) was unable to affect the detection of a 23-Hz signal (non-Pacinian). A 23-Hz masker (non-Pacinian) did effectively mask a 300-Hz signal (Pacinian). It was shown that the cross-channel masking is due to the spread of the mechanical disturbance from the thenar to the fingertip and that the amplitude of the masker was sufficient to excite both systems. Results will be discussed within the context of a duplex mechanism for mechano-reception. [Work supported by NIH.]