Subjects made delayed pitch comparisons when the tones to be compared were separated by a retention interval during which six extra tones were interpolated. All tones were 300 msec in duration. The pause between the last interpolated tone and the comparison tone was either 500 or 2000 msec; otherwise all pauses were 500 msec. The standard and comparison tones were accompanied by tones of lower pitch which the subjects were instructed to ignore. In some conditions the harmonic intervals formed by the standard and comparison combinations were identical and in others they differed. It was found that when the standard and comparison tones differed but the standard and comparison combinations formed identical harmonic intervals, there resulted a substantial increase in errors of misrecognition. However, this occurred only with the longer delay between the standard and comparison tones and not with the shorter delay. It appears that during the extra delay pitch information decayed rapidly, resulting in judgments based on harmonic interval rather than pitch.