The crosstalk fault effects in deep sub-micron VLSI, namely, glitches and the crosstalk-induced delay, are investigated. The origin of their occurrence, relationship and importance in circuit operation are elucidated. It is shown that the crosstalk-induced delay is only superposition of the induced glitch with the original signal delay on the affected victim line; and crosstalk-induced delay is more important in affecting the circuit performance, and should be considered in more details for testing. A scheme which is to detect both types of faults in a unified way by just detecting glitches is proposed and studied considering the manufacture process variation. In this way, detection of crosstalk-induced faults becomes much easier.