Identical to the standard minor scale (the natural minor scale), except that the seventh note is not flatted. The result is an interval of a 1 1/2 steps between the sixth and seventh tones of the scale, and a few elements of chromaticism. Some quick examples of harmonic minor scales:
  • A Harmonic Minor contains the notes: A B C D E F G#
  • Bb Harmonic Minor contains the notes: Bb C Db Eb F Gb A
  • D Harmonic Minor contains the notes: D E F G A Bb C#
One immediate consequence of the large interval between the sixth and the seventh is a change in the kinds of chords that can be played within the scale. Specifically, we have the augmented triad, the minor-major seventh and the fully-diminished seventh. The chords that can be played using the tones of A Harmonic Minor are:
 i   ii0   III+   iv  V   VI    vii0
Am  Bdim    C+    Dm  E   F    G#dim
Am7 Bm7b5 Cmaj7+5 Dm7 E7 Fmaj7  G#07
Note that maj7+5 refers to a major seventh chord with an augmented fifth. When referring to a triad, the + implies an augmented fifth, but the + can also be used to notate other augmented notes: Gmaj7+11 includes the notes G B C# D F#

Harmonic minor is often used briefly in pieces written in the natural minor scale, if only to play the fully-diminished seventh or dominant fifth chord before resolving back to the tonic. Interesting chromatic effects can be achieved by playing both the seven and the flat seven in a single phrase. Noted guitar bad-ass Yngwie Malmsteen uses the harmonic minor scale all the time.