If a second succeeding pulse arrives immediately after a first preceding pulse in the output from a non-retrigerable monostable multivibrator, the width of the succeeding pulse is somewhat shortened. Using a time-to-amplitude converter followed by a multi channel analyzer, the pulse-width shortening of the succeeding pulse was measured as a function of the time interval between the two pulses. It was found that this effect was highly dependent on the resistance of an external RC time constant circuit. Similar measurements were also carried out for nuclear instrument modules involving the monostable multivibrator circuits.