Field recordings of underwater sounds of the toothed whaleMonodon monocerosexhibit consistent characteristics not noted in other odontocetes. The sounds were mostly narrow‐band regularly spaced, and often high‐frequency (to 24 kHz). The fundamentals of individual sound pulses ranged from 1.5 to 24 kHz. Both clicks (short pulses produced at repetition rates up to 300/sec) and tones (to 0.1‐sec duration) were noted.