An imperfect cadence is any cadential progression that ends on V. Three are particularly common and two of these involve the relationship of a perfect fifth. The third in the example below (C) is discussed along with other progressions that involve the interval of a second.

The progression from I to V (A in the example below) is the exact reverse of the perfect cadence and is therefore has the opposite effect. If the perfect cadence is considered as a closing gesture - bringing a sense of resolution- the progression from I to V is an open gesture. At the beginning of a phrase an opening gesture might be expected, but when a phrase ends I - V (an imperfect cadence) it introduces a tension that listeners have come to expect to be resolved by a later perfect cadence.

The progression from ii to V (B in the example above) also involves the relationship of a fifth. This is involved in the most common cadential progression - ii-V-I). When it apppears at the end of a phrase it therefore V sets up and then denies the expectation of a further progression to I. Again, this could be interpreted as creating tension. This progression often appears, as in the example, with the ii in first inversion.